Pregnancy Scare! Help!

Mikalyn
So on the 11th of June, my boyfriend and I "slipped" up and had unprotected sex. It was only for a few seconds and he didn't cum. I had also previously given him head, so I don't think there would have been a lot of precum if that sounds logical to anyone else. 
I'm not late yet, however I have been stressing about this for days. I'm only 17 and soon to be a university student in the fall! I really can't have a child right now and I'm so freaked! Help?? Could I be pregnant?