I oversleep fajr, woke up prayed it. Then went back to sleep. Woke up again and it was dhuhr time. I (MAY!) have gone to the bathroom to pee then spending more time before praying dhuhr prayer. Then towards the end of asr prayer I was about to pray but saw my menses.Now i don’t know when exactly the menses started. It could have started all the way towards the end of fajr (if I didn’t use the bathroom in dhuhr, I probably did but I’m not 100% sure, but most likely I did use it. But also I may have used the bathroom but not wiped to see blood

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, sallallaahu`alayhi wa sallam, is His slave and Messenger.

If something is likely to happen in one of the two times, then it is attributed to the most recent time (the second of them), so if you doubt whether you saw the menstrual blood before noon or after it, then the basic ruling is that you saw it after noon, and accordingly, according to the view of the Majority of Scholars, when you become pure from your menses, you must make up that noon prayer. Malikis are of the view that if you menstruate before the time for the prayer is short (i.e. before the time of the prayer is close to its end), then you do not have to make it up in this case, and Sheikh al-Islam Ibn Taymiyyah  agrees with them regarding this. So, to be on the safe side you should make up that prayer, for the matter, Allah willing, will be easy.

Allah knows best.