I had unprotected sex one weekend (Oct 2-4, 2009), using the pull out method. I was pretty positive nothing happened, so I didn't follow up an emergency contraceptive. One week later, I had unprotected sex again (Oct 9-10, 2009), still positive nothing happened, but decided to get the Plan B pill to be safe. I took it within 3 days (Oct 12, 2009, within the 72 hour window) of the second incident and received my period 6 days later (Oct 18, 2009). The physician I talked to said that Plan B will force me to have a period this month, so I may possibly be pregnant from the first unprotected sex incident. She advised me that if I have not received my period by the end of this month (Oct), then I should take a pregnancy test; and I should receive my next cycle around the same time next month (Nov), but if I don't I should take a pregnancy test. I took a pregnancy test 5 days after taking Plan B (Oct 17, 2009; I just had to know, even if it may/may not be accurate at the time), which turned out to be the day before my period started, and it showed up negative. But I read in another thread that Plan B does NOT force you to have a period (but it didn't have an explanation as to why). Later that same week of taking Plan B, I went to get birth control (I chose NuvaRing). I read on the NuvaRing website that you should start using their product before or on the 5th day of your cycle. But I'm not sure if I should in case I may be pregnant. So, I guess what I want to know is: After I've received my period after taking Plan B, that means I'm not pregnant, right? Can I start using NuvaRing on the 5th day of my current cycle, or should I wait for my next cycle (in Nov) to be certain that I'm not pregnant? Sorry if it's confusing, I'm pretty confused myself and this is the best I can explain my situation. Thank you for your time and input.