Her brother was her guardian for marriage because her father did not approve of the marriage, then he agreed one year later
Question

                I have a question regarding the validity of my Nikah. I got married one year ago with my brother as my guardian, because my father refused to marry me. After one year, my father had happily accepted my marriage. I am sometimes worried about the validity of my nikah, was it islamically correct?
Praise be to Allah.(1)This advice is addressed to parents:  
The 
          duty of parents is to hasten to arrange the marriages of the women who 
          are under their guardianship, if someone who is compatible proposes 
          marriage and the woman agrees to that. Whoever does not do that is going 
          against the command of the Prophet 
          
          (peace and blessings of Allaah be upon him). It was narrated from Abu 
          Hurayrah that the Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) said: “If there comes a 
          proposal of marriage from one with whose religious commitment and character 
          you are pleased, then marry [your female relative under your guardianship] 
          to him, for if you do not do that, there will be fitnah (temptation, 
          tribulation) on earth and much corruption.” (Narrated by al-Tirmidhi, 
          al-Nikaah, 1004; classed as hasan by al-Albaani in Saheeh 
          Sunan al-Tirmidhi, no. 865).
It 
          is not permissible to treat them with harshness [cf. al-Nisaa’ 4:19 
          – interpretation of the meaning] for any reason that has not been prescribed 
          by Allaah and His Messenger. “Harsh treatment”, as defined by Ibn Qudaamah, 
          means, “preventing a woman from getting married to someone who is compatible, 
          if she asks for that and if each of them wants to marry the other.” 
          (See al-Mughni, part 7, p. 24). Parents and guardians should 
          hasten to marry the women under their care because that will protect 
          them from falling into that which Allaah has forbidden, and so that 
          the guardian himself will not fall into that which Allaah has forbidden 
          of the sin of treating them harshly. The basic principle is that harsh 
          treatment on the part of the guardian by not letting her marry someone 
          compatible is haraam, because it is oppression and harming the woman 
          by depriving her of her right to marry someone she wants. That is because 
          Allaah forbade that when He said, addressing guardians: 
“… 
          do not prevent them from marrying their (former) husbands…” [al-Baqarah 
          2:232 – interpretation of the meaning].
(2)The ruling on this matter may be one of two:  
The 
          first is that if the closest relative or guardian of the woman was treating 
          her harshly by preventing her from getting married, then it is OK for 
          a more distant  relative to act as her guardian in marriage, even 
          if the closer relative is present, because in this case he has no right 
          to be her guardian.  
Al-Mirdaawi said: “The phrase ‘if the 
          closer relative is preventing her from getting married then the more 
          distant relative should act as her guardian in marriage’ is the correct 
          view in the madhhab; most of our companions share this view… Shaykh 
          Taqiy al-Deen (may Allaah have mercy on him) said: one of the forms 
          of ‘harsh treatment’ is when no one is proposing marriage to her, because 
          of the harshness of her guardian.”
(al-Insaaf, 
          part 5, p. 74)
Shaykh al-Islam Ibn Taymiyah said: If 
          she likes a man and he is compatible with her, then it is obligatory 
          for her brother or her (paternal) uncle to act as her guardian in her 
          marriage to him. If they treat her harshly and prevents her from marrying, 
          then a more-distantly related guardian may marry her to him.”
(al-Fataawa 
          al-Kubra, part 3, p. 83)
Ibn Qudaamah said: “If her more-closely related guardian 
          treats her harshly (by not letting her get married), then the guardianship 
          passes to one who is more distantly related. This was stated by Ahmad…”
(al-Mughni 
          by Ibn Qudaamah, part 7, p. 24)
Shaykh Ibn ‘Uthaymeen said: If a father prevents his 
          daughter from marrying someone who is compatible, then guardianship 
          passes to a more distant relative, the closest then the closest.”
(Fataawa 
          Islamiyyah, part 3, p. 149)
The 
          second is when a more distant relative has arranged the marriage when 
          the closer relative is present and was not treating her harshly (by 
          preventing her from getting married).
Al-Mardaawi 
          said: “If a more distant relative arranged the marriage for no reason, 
          or a non-relative arranged the marriage, then this is not valid.” (al-Insaaf, 
          part 8, p. 82).
Al-Bahooti 
          said: “If a more distant relative arranged the marriage with no reason 
          why a closer relative could not have arranged it, then the marriage 
          is not valid… because the more distant relative has no right of guardianship 
          if a closer relative is present.”
(Kashshaaf 
          al-Qinaa’, part 5, p. 56)
This issue may be examined further. If 
          the closer relative approves of this marriage, what is the ruling? And 
          if the closer relative approves of this marriage, does his approval 
          make the marriage valid or not?
The 
          scholars said: If someone arranges the marriage when there is someone 
          else who is more entitled to guardianship and he is present, and is 
          not treating her harshly (by preventing her from getting married), then 
          the marriage is invalid. This issue includes three rulings, the first 
          of which is that if the more distantly related guardian arranges the 
          marriage, when the more closely related guardian is present, and she 
          accepts the proposal of marriage without the permission of the closer 
          relative, then it is not valid.
This 
          was the view of al-Shaafa’i.
Maalik 
          said: It is valid, because this is a guardian, so it is permissible 
          for him to arrange the marriage with her permission, as is the case 
          with a closer relative. 
The 
          second ruling is that this marriage is null and void; it was not done 
          with permission or with proper permission, and it cannot be made valid 
          with the approval of the closer relative. Marriage in all such cases 
          is invalid, according to the more sound of the two reports. This was 
          stated by Ahmad in several places, and this is the view of al-Shaafa’i, 
          Abu ‘Ubayd and Abu Thawr.
Another 
          report was narrated from Ahmad, in which he said that it depended on 
          approval, if approval was given it was permissible, and if approval 
          were not given, it was invalid.
Inkaah 
          al-Fudooli.
According 
          to the terminology of the fuqaha’, the fudooli means one who 
          interferes in the rights of another without any permission from sharee’ah, 
          because his interfering is not based on any rights of ownership, trusteeship 
          or guardianship.
(al-Mawsoo’ah 
          al-Fiqhiyyah, part 32, p. 171)
The 
          fuqaha’ differed concerning the ruling on a marriage arranged by a fudooli 
          without any rights of guardianship or proxy:
The 
          Hanbalis and al-Shaafa’i in al-Jadeed said that the marriage 
          arranged by a fudooli is invalid and the approval of the guardian has 
          no effect (i.e., the marriage contract must be repeated).
The second view is that of Ahmad, according 
          to one report narrated from him, and of Abu Yoosuf, which is that the 
          marriage arranged by a fudooli is valid, but it depends on the approval 
          of the guardian. If he gives approval then it is OK, but if he disapproves, 
          it is not valid.
(al-Mawsoo’ah 
          al-Fiqhiyyah, part 32, p. 175)
In 
          conclusion: some of the scholars have said that the marriage contract 
          is valid if the guardian approves – as you have seen – and if you want 
          to have more peace of mind and avoid an area concerning which there 
          are differences of opinion among the scholars, then do the marriage 
          contract again. All that is needed is the proposal from your guardian 
          – your father – and acceptance from the husband, and the witness of 
          two Muslim men, and repentance for what has happened. 
We 
          ask Allaah to give you strength.