I've been on the BC Mononessa for 4 months now without problems, I am on the 5th day of my 4th pack and my boyfriend and I had sex with a condom but it slipped off and when we got it out of me, it was almost completely empty of any semen. I've not missed in the past 4 months, i have been on time these past 5 days but I was 2 hours late on one of my placebo pills that I just ended (idk if that effects it?). should I take Plan B? what are my chances here? thanks