Help!

So I haven't had my period since last month! And I'm 5 days late. I took a pregnancy test at the beginning of the month when I got my birth control and it was negative. But that night me and my boyfriend had sex, and didn't use a condom at first, he didn't finish till he put a condom on though. So I took another pregnancy test two days ago and it was negative. But I still haven't had my period! What do I do?