Could I be Pregnant?

So, I always freak out about this. But. Me and my boyfriend tried it raw (no birth control) but he didn't ejaculate in me. We went for two rounds, and I'm pretty sure I was fertile during this time. But no sperm (unless precum) went in me. Could I be pregnant? Is this something I should worry about? Or should I calm down? I'm 17 and my period is supposed to be in 10 days.