Spotting?

I've been on birth control since November and have never spotted before. I missed a day last week and began spotting, the same day my boyfriend and I had sex with a condom. I stopped spotting for a day and then we had sex again, but he ran out of condoms. He pulled out but wasn't sure where "it" went. I began heavily spotting again today, and my period is due in 3 days. I know I shouldn't freak, but I'm worried I'm pregnant.