why do i have a heavy flow ???😫

so im very tiny... i only weigh 115 pounds and my height is 4"11.. Im 22 years old.. and i deal with heavy flows since i started my period when i was 12.. It sucks..and i hate it... i also get the worse cramps in history. I have tried the Depo shot birth control but it didnt work well for me,, what should i do