UPDATE I think I’m just crazy

I feel like i could be pregnant despite the overwhelming evidence against it. I’m on birth control, i’ve had regular periods, but i’ve gained a little bit of weight and I’m super moody/emotional lately. I also have issues with nausea but lately everyday i’ve woken up nauseous and i’ve been having more tummy issues. I’m pretty sure I’m not pregnant but i’m paranoid. I’m pretty sure i had sex during what would be my fertile window (but since I’m on bc my fertile window isn’t really a thing right?)

update** I had sex on march 8 and 9 and i started my period on march 14 or 15 and it was heavier than I’m used to

i’ve been super tired today with back pain that i’ve only experienced during my periods wo birth control. I haven’t taken a test yet only bc i live in a tiny ass town where i cant find one