A little worried after taking Plan b.?

I had unprotected sex with my bf for like 2 minutes and then got scared and told him to stop. He didn't ejaculate inside of me but I took Plan B 8 hours after the incident. This is the third time I have taken it and each time I have bled about a week after but this time I have not. I have all kinds of PMS symptoms and it feels like I will start my period soon. It's not late and I still have a week til it's due but what are the chances of being pregnant if I took Plan b 8 hours after intercourse and he did not *** inside me.