When is CD1? Need to confirm for fertility medicine

Hey ladies, I need to determine my CD1 (for fertility medication purposes).

8/14: I started getting really bad cramps in the morning and only saw blood or anything when wiping. I put on a pad and went to work. First bathroom break I went and the pad was empty however when I peed I had red flow when wiping so I put in a tampon. After 3 hours I took it out it was more brown and brown discharge, and then for the remaining of the day I wore a pad and it was only spotting with minimal in the pad.

8/15: Woke up and had cramps. Went to the bathroom and had full red and some clots. Put a tampon on in and called it a day. Again, when I removed it tampon wasn’t very full and then remaining of the day was more spotting/clear mucus and red but again not much of a flow per say.

8/16: Today is a light period flow. Consistent but very light, bright pink:red. Doesn’t fill a pad though.

I’m thinking yesterday was CD1 but would like others inputs. However I get thrown Bc I did have a full red wipe on 8/14. All very confusing!