I missed my period. What's going on?
It is really normal for girls to experience irregular periods when they first start menstruating. A girl might skip a period and then have a longer or shorter period. And then she might go back to a normal period.
There are many reasons why a girl might miss a period, including the following:
A missed period can also be the first sign of a pregnancy. If you have had unprotected vaginal intercourse, then it is important to find out whether you are pregnant as soon as possible. Get a home pregnancy test from a store or, better yet, make an appointment with your doctor or at a clinic.