Late Period After Birth Control & Plan B: Causes & What to Do

Question
Me and my girlfriend are both 19 years old and she has been on the birthcontrol pill for about 3 months now. Since her last period we have had intercourse twice within two weeks, where i have ejaculated inside of her, but we took Plan B right after both times for extra precautions. She usually gets her period 3-4 days after getting starting the white sugar pills, but today is the 4th day and she has not gotten it yet.  Why could this be? Thank you.

Answer
Most likely your girlfriend's period is late because of the Plan B.  It tends to cause early and late periods.  As long as she's on the pill and takes it the same time every day, she doesn't need Plan B.  The pill is highly effective, and almost all pregnancies on the pill are because of missing pills.  Some women also stop getting their periods after being on the pill for a while, so that could also be happening.  It's probably best that she do a pregnancy test, just to make sure.  However, I doubt very much that she's pregnant.  Best wishes.