Vvvfl and bleeding

Cortney

I have had multiple vvfl on various tests the last 3 days but started bleeding yesterday (day of expected period) and faint line still there today, not getting darker and staying the same. Im guessing it’s chemical pregnancy but how can I be sure? I’m supposed to start Letrozole on day 2 or 3 but unsure if this is period and I don’t want to start if for some reason I am pregnant. Anyone have insight or experience with this?