Pregnancy or hormonal inbalance?

Sooo, last Saturday I had unprotected sex. We weren't sure if he came or not so I took a plan B pill probably up to 5 minutes after. The friday after this happened I had bleeding that was as heavy as a normal period (leaked through my pants!!!) so I thought I was just starting early but now it looks like i'm not bleeding anymore?? Could I be pregnant or is it a side affect of the pill and how its affecting my hormones?