Birth control question


Okay so I recently had unprotected sex after thanksgiving so that was last month but the only thing is I only had sex once through my ovulation and I haven’t took my birth control pills after the unprotected sex and like I don’t take my pills correctly could I still become pregnant?? My period is supposed to start December the 16 but it hasn’t yet so can anybody try to explain on what should I do or what should I do? And since I don’t take my birth control pills correctly could my period still go off the pills format because the last pill in my pack is Saturday and that day will be December the 16 so can y’all please try to explain to me thank u no negative comments please thank u.