What can cause you to have very irregular bleeding to were u bleed for weeks to months straight sometimes

I've been on birth control since the 7th grade (20 now) and I've always had irregular bleeding since I started birth control (I only started birth control that young cause my" normal" period when I started would make me throw up cause it caused so much pain along with very heavy bleeding and swelling feeling) I've been on the shot pill and now the implant... I'm tired of bleeding so much.. its starting to interfere in a lot of things especially with my boyfriend (He at least understands but it still is irritating) the doctors have done a D&C; and pap smear and say I'm fine and don't seem to really care they gave me a crap ton of hormone pills and said take it aggressively and of course that didn't help... I don't know what to do anymore especially cause my insurance was turned off I wanna get the implant taken out and try the birth control since I've been on it for about 7years but I'm terrified that heavy bleeding and awful pain will come back... Has anyone been through this or close to it ?? I'm just trying to figure out what it could possibly be since the doctors aren't trying to help..