SOS The possibility of me being pregnant? HELP!

I'm 17 and I've been dating a guy the same age as me for over a year and a half now. A little while ago we both decided to have sex for the first time. Well only the third time we had sex the condom broke right before he finished and he came inside me. I'm also on birth control and I'm usually pretty good about taking it but that specific day I took it 5 hours late. It was also just a few days after my period so I wasn't very fertile. I also took plan B that same night because we are both extremely paranoid. He says I should be in the clear but I'm experiencing cramping and white discharge but my period isn't for another two weeks. I'm scared this could be a symptom of pregnancy? I can not be pregnant, my father would literally kill me and I still need to graduate. Most people still think I'm a virgin! Please help me! What do you think?