I am 17 and I had unportected sex but my boy friend didn't . However there was precum. I heard that pre may carry sperm but if he urinated before we had sex then there shouldn't be any sperm in the precum. But I did start my period the very next day. Then this month I missed my period but I don't know if it is because of all of this stress or what! Is there a chance I could be pregnant? Please help I'm freaking out!