Late period

I started my birth control 8 days before my projected start date for my period. Ive now officially missed my period. Is this normal to happen? ive only been on Birth control for 2 and a half weeks i didn’t expect it to settle in so quickly i guess. It would really help if someone can educate me on this I really hope i’m not pregnant. Also my bf came inside of me a few days ago but i took plan B within 14 hours of that happening