I was waiting for my period to start so I could begin taking Yaz on the Sunday after my period started. I had sex with my boyfriend on Wednesday morning and the condom broke. I took Plan B on Thursday night. I have taken Plan B before and I got my period within a week of taking it, but now that I've taken Plan B I'm afraid that if I get my period and I start the birth control, the early period might actually have been breakthrough bleeding and not a real period. So should I just assume that the bleeding I get is my period and start the birth control as if I had never taken Plan B? If it ends up having been breakthrough bleeding and I started the birth control anyways rather than waiting to make sure I was definitely having my period, what risks are involved?