Assalaamu alaykum. I am really confused with regards to the end of menses. I know that it is indicated by either complete dryness or the emission of white discharge. I check three times at once to make sure that I am pure and in case the tissue did not enter the private part properly the first time or so. For example, at the time of the Fajr, the first two times, it comes out clean, and the third time I see a very slight yellowish discharge. As it was less yellowish in color than what I saw the previous night before sleeping, I considered it menses and took a shower in the morning/afternoon when the tissue came back clean with a clear discharge on it all three times. To be on the safe side, I made up for the Fajr prayer in case I have made a mistake in determining the end of menses. Please let me know if what I did was correct as this puts a lot of stress on me every month during this time and I think that I might be sinning if I miss a prayer because of this confusion. May Allah reward you well.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

We advise you to ignore obsessive doubts and to not pay any attention to them. You do not have to check repeatedly to make sure about the purity.

Whenever you insert a tissue in your private parts and it comes out clean without any trace of blood, yellowness, or brownness, then hasten to perform Ghusl (ritual bath) and pray. After this, do not pay any attention to what you see of yellowness or brownness because after purity it is not considered as menses.

For more benefit, please refer to fatwa 31013.

Allah knows best.