what do I do?

So I was supposed to get my period Sunday and it's been almost 4 days and I still haven't got it! I had sex with my bf like every week and we use condom but sometimes he takes it off before he's about to cum so he just pulls out, but idk if I should worry about that! And I've been feeling dizzy and sick... Idk if it's just my hormones or stress because of college. Can anybody tell me what I'm supposed to do?!