I've fainted 3-5 times in my life but my doctor says I'm fine??

Some people just faint more than others. The sight of something unpleasant, not eating regularly, not taking in enough fluids each day, dieting, all can contribute to a teen fainting. Almost all females who have their periods are anemic but most do not faint because of this. It just makes them more tired all the time. On your next visit with your doctor, you can ask him to test your blood to see if anemia is a problem for you but just having your period for one year - probably not.