Pregnancy scare???

So many boyfriend and I have had sex twice in the last week/week and a half. Well I started on my green pills two days ago and I haven’t gotten my period yet and I know it could be just me messing up on a pill previously but I’m freaking out. We’ve had sex maybe 3 times in the month of December and I’ve been trying really carefully to remember my pills but no that I haven’t gotten my period idk what to do! ): help please