It is permissible for the woman’s maternal uncle to be her guardian for the purpose of marriage if he is appointed as a proxy by her original guardian
Question

                I have been married for 3 years now and I keep having doubts about whether it is valid or not. I cannot distinguish whether the doubts are true or false waswas from the shaitan. My doubt mainly arises from the fact that since my dad was the wali and he appointment my maternal uncle to be the wakeel, but my father is someone whose religious knowledge and comittment i did not trust at that time, due to his lack of knowledge and implementation. I recently did my nikka again to be on the safe side but this fatwa website told me that according to imam shafi if one wants to redo the doubtful marriage contract they have to divorce the husband first and then redo it. If that is the case then in the case my last marriage was valid then this will be my third divorce after which i cannot remary my husand again but if previous marriage was not valid then according to them i will be committing haram, but I never knew that if u want to redo your nikkah you have to get divorced first. Please help me and advise me in my situation as I dont know where I stand, Is my nikkah valid? Shouldn't get your nikkah done again be okay in case you have doubts, that is the idea i got from reading your website.
Praise be to Allah.In order for the marriage to be valid, the contract must be done by the woman’s guardian or his proxy. Whether this proxy is one of their relatives or otherwise, the marriage contract done by him, based on that appointment as proxy, is valid and there is no problem with it. 
If her guardian appointed the woman’s maternal uncle as his proxy, for example, or any other man, to do the marriage contract for her, the marriage contract is valid. This has been explained in fatwa no. 153602. 
Based on that, your marriage contract is valid and there is no problem with it, because even though your father did not do it directly, it was done by his proxy, and that is permissible. 
So ignore these insinuating whispers (waswaas) that the Shaytaan is sending to you, and understand that you do not need to re-do your marriage contract because it is valid. 
And Allah knows best.