Help me

I’m still so very confused my period is still being wonky... it’ll stay on for a few mins then stop. It’s been on for 12 days it’s off now. But if I try to do something sexual or just get horny I’ll start it again then it come off within the next 30 mins. I’m on birth control and I love really don’t know what’s going on. Lady’s I really need your opinion because I’m clueless and helpless