Kinda freaking out

So when i was like 15 i got my period on and off but it would happen every six months and then the period would last months!! And its extremely heavy. I can go through. Giant ad and super tampon at the same time in bout 15min. Now im 17 i havent had my last period since the beginning of February. But that only lasted a week. But im freaking out idk if this is healthy. I dont play sports, im average weight and stuff . so i have no idea whats going on