Hi I'm a 15 year old girl and I have been on birth control for over a year now to keep my period regular. Throughout this week I have had light pink/ brown blood it is very light.. and my period isn't suppose to come until next week. I have not had sex lately. Is this normal? Should I be worried? Please help!

It can sometimes happen that break through bleeding will occur while using birth control pills. This may be what is happening in your situation. Have you been taking the pill on a regular basis; not missing any? If you have missed some here or there it can decrease the effectiveness so pregnancy can become a greater possibility.
When you say that you haven't had sex lately, how long ago is "lately"?

See what happens when you would expect your period. If it doesn't show, try a pregnancy test to rule out possible pregnancy.

Remember too, that birth control pills, when taken correctly, lower the chances of an unplanned pregnancy, but they don't eliminate it altogether.