After her menses dries up, there is a discharge, so does she have to wait?
Question

In the past, I used to know that my menses had ended by seeing the white discharge, but in some months I would wait until night on the eighth day, but I would not see anything except dryness. Then I would do ghusl and not wait another day until the discharge appeared, because the dryness would go on for a long time, and I was afraid of missing prayers as a result. But last month I waited until after midnight (on the eighth day) and I saw the discharge, so I got worried that during all those months when I thought that my menses had ended on the basis of dryness only that I had been too hasty, and that I should have stayed up all night until dawn, until I saw the discharge, so that I would not miss the prayers. Please advise me, may Allah reward you.
Praise be to Allah.Firstly:
The end of menses may be determined by one of two signs, the first of which is cessation of bleeding and dryness of the place, meaning that if the woman were to insert a piece of cotton and the like, it would come out clean with no trace of blood or yellowish or brownish discharge on it.
The second sign is the emission of the white discharge; some women do not see this discharge.
What you have mentioned, that you used to rely on seeing the dryness and not wait to see the discharge is the right thing to do. An-Nawawi (may Allah have mercy on him) said: The sign of the cessation of menses and that the woman has become pure is when the bleeding and the yellowish and brownish discharge ceases. When they cease, the woman becomes pure [i.e., her menses has ended], regardless of whether any white discharge is emitted after that or not."(Al-Majmu‘  2/562).
Secondly:
If your menses comes then stops, and the place becomes completely dry, then you have become pure [your menses has ended] and you must fast and pray. You do not have to stay up all night and wait for the white discharge to appear; rather you should not miss prayers for the sake of waiting for that.
But if the place has not become dry, and there is some yellowish or brownish discharge, then you should not be hasty until you become completely dry or the white discharge appears. The women used to send to ‘A’ishah (may Allah be pleased with her) pieces of cotton on which there were traces of yellowish discharge, and she would say to them: Do not be hasty until you see the white discharge. Narrated by al-Bukhari in a mu‘allaq report.
And Allah knows best.