So funny story my boyfriend and I wanted to try anal and I heard that you can't get pregnant from it so we went without a condom. I couldn't really tell what hole he was going in so I asked him to check l, he said he was in the right hole. I checked and he was not! He was in my vag. He hadn't got very far in but I still wanted to be safe and take Plan B. I'm also on the pill. My period hasn't started yet (I was due on Wednesday) and this happened almost a week ago. Is this just a side effect of Plan B? Or should I start freaking?