I'm scared i could be pregnant?

Okay , so me and boyfriend had sex on may 11th . 7 days after my period . We played around a little and he had already came But for about 25 secs he went inside me with no condom. Then he stopped and put on a condom. Even though we didn't do nothing until after he came ,i still think that i might be pregnant. I've always had a irregular period . But for some reason mines hasn't come yet. I really don't see any signs on pregnancy but i've been worrying ever since. I Don't if it's late because i'm stressed and worried , or if i'm pregnant . PLEASE HELP !! : /