Panicking Help

So I've been on birth control for a few weeks and my partner and I had unprotected sex 4 days ago as of posting this.

when I was prescribed I specifically asked if it would interfere with my mother medications and my physician said no.

I visit my nurse practitioner today, and APPARENTLY ONE OF THEM DOES.

I take a mood stabilizer called Lemotragine which interferes with birth control apparently. I couldn't tell you exactly which one I'm on, one that supposed to help my skin.

My parents don't know I'm sexually active (and they'd flip shit if they did) but they do know I'm on birth control. My mother even expressed concern about me sleeping with peoplewhen I got on it.

Anyway, I'm stacking my period for 3 months... and apparently I had sex during my "fertile window." so I'm really nervous that I might be pregnant. what are the chances that I could be?