I need advice

I have had my period for 4-5years now my cycles are weird I will go multiple months like I’m talking from august to May which is my longest has I I’m worried why is it like that my doctor says if it doesn’t like regulate I’ll have to get like an ultrasound ( I don’t even know why) My periods are really heavy and I have bleed through super plus tampons in under and hour pls help any advice is appreciated