Very Long Period

I'm 17 and I've been getting period for four years now. From the beginning of the year my period has lasted for over 40 days. The previous time I had my period it was around 47 days. After 6 weeks, I got my period again for now 45+ days. It is not spotting, it is around medium heaviness constantly. When it happened to me at the beginning of the year I was prescribed insulin regulating medication which ended my period. I'm still taking them and my period continues like this. Please help!