It sounds like your periods are quite unusually heavy. Small clots can certainly be normal but I’m concerned about the size of your clots and also how heavy your flow is. You certainly would be a young lady that I would be investigating further. Have you seen a gynecologist yet? Have you had any blood tests to see if there is a problem with your blood clotting? Have you had an ultrasound yet? These are all things I would be thinking about after I had seen your detailed history and examined you. I would recommend you see your doctor.