Could I be pregnant?

Natalie

My name is Natalie. I’m 18 and I’m from Arkansas.

I started my period Feb. 16 and I receive my birth control shot on Feb. 19. My period “stopped” on Feb. 21 and my boyfriend and I had sex on the 22 (his birthday). We didn’t use protection and he didn’t pull out. Then I started bleeding again the next day (Feb. 23) and then it stopped. What does this mean?