When did I conceive?

Kenna • CNA 👩🏼‍⚕️ bfp 04/02/19 - due 12/10/19 💙 born 11/16/2019 🌈 surprise bfp 02/08/20 - due 10/11/20 💙 born 09/16/2020 Mom to my angel baby 👼🏻 Endometriosis, hypothyroid, hashimoto, inflammatory arthritis & connective tissue disorder

Just wondering when I could’ve conceived. I just got my first PP period. (Has my son 11/16) Tested positive on Feb 8th, though I did have a negative Feb 3rd. My cycles pre pregnancy were 30-35 days and the 8th was the day my period was due (and the 35th day). My first ultrasound is Feb 24th.