Understanding a Late Period After Emergency Contraception & Birth Control

Question
Here's the story! My last regular period was on July 28 and my regular cycle length is about 28 days. I had unprotected sex on Aug. 11 and the only safety measure used was withdrawl. The very next day, I would say within 6 hours I bought Plan B and took it. Then on Aug. 19 I had what I thought was my period although it was rather earlier; Plan B said it could mess up your period. Now to make it even more difficult, I started taking birth control that following Sunday and now here I am, Sept. 18, still waiting on my period. I'm on the dark green placebo pills right now in my birth control pack and I read that typically that is when you get your period. I'm scared that I might be pregnant, although I don't understand how when I took Plan B and am now on birth control. I'm just hoping that it's only the birth control pills messing up my period since this is the very first time I'm taking them? I have noticed though that I have been gaining a tiny bit of weight around my stomach which is usually very flat and my breasts are growing ever so slowly; but am hoping it's only side effects of the birth control pill...By the way I'm 20 years old if that helps! I look forward to hearing your response!

-Lily

Answer
Hello Lily,

I also suspect that you might be pregnant, but you'll need to do a test (first morning urine) to know.  Plan B greatly reduces your chance of getting pregnant, but doesn't eliminate it.  Assuming you took your last active pill on Saturday, most women would have gotten a period by late Wednesday.  If you are pregnant, a pregnancy test should be positive.  If it's negative, then I guess the absence of a period must be from the pill.  In that case, I would keep taking the pill and see whether you get a period next month.