I am on a 28 day cycle and my period comes at the same time every month so I'm on a pretty set in cycle. I am also on birth control and are usually pretty good about taking that on time also. During my last period, which was about two weeks ago, I had sex on my last day and the condom broke. I was really worried so I took Plan B about an hour later. I'm still somewhat nervous and I was just wondering how big my chances are of becoming pregnant?