I Had Unprotected Sex With My Boyfriend And It Was

I had unprotected sex with my boyfriend and it was our first time. I was a Virgin and he didn't ejaculate in me and he didn't go all the way in. I just had my period that morning. I took plan B two hours later and took as much vitamin C as I could the next day. What are the chances of me getting pregnant. The only thing that could have gone in me is pre-cum. I know itight only take that. I'm just really scared and want to know my chances of getting pregnant.