Am I pregnant? Could it be possible?

Hi, my boyfriend and I were fooling around and then I sucked on his penis, he finished in my mouth. Afterwards, (wearing clothes both he and I) except his pajama pants where pulled down to reveal his boxers, I rubbed myself (wearing pants and panties) on him and I was wondering if any of the left over semen could go through my clothing or somehow make me pregnant. Could it? I'm scared. But when I checked my pants there was a wet spot, I'm not sure if it was from me or him. I'm scared, could I be pregnant? And this was 2 days after my period ended. I'm not taking any birth control either.