What Causes Irregular Periods?

25，5ft5, 60kg. Hi can someone please advise. Very irregular mensis cycle. Been to a number of hospitals, did all the scans. Was put on hormones, but stopped taking them along time ago. Got different diagnosis from diff docs. I would like to get to the root of what's wrong and stop taking meds for something I don't understand. Will be visiting the hospital next month. Please advise