I think I'm pregnant

I'm 16 and I had unprotected sex with my boyfriend he did ejaculate inside of me. I'm not sure if my birth control was updated enough I got the shot back in October. This happened 3 weeks ago. And now I'm eating things I don't like haven't had morning sickness yet but I have noticed that my belly is partially extended but idk if it's in my head or not. Please help.