How to manage menstrual irregularities and abnormal bleeding?

Hello, doctor.

I am a single female, soon turning 21, with a height of 5 feet 2 inches and a weight of 119 pounds. I have been experiencing menstrual problems for the past eight years. Eight years back I had abnormal bleeding along with golf ball-sized blood clots (two to three). I promptly visited a doctor who prescribed medication to stop the bleeding. After that, my periods were irregular but somewhat normal. Typically, my periods last for up to 15 days. I had another episode of abnormal bleeding one year later. I consulted a doctor there who performed a pelvic scan and diagnosed me with PCOS (polycystic ovary syndrome). She prescribed birth control pills for three months, and during that time, my periods were normal, lasting only seven days. However, after finishing the course of the birth control pills, my menstrual issues again resurfaced after seven years. I started my period, which lasted five weeks. I noticed that the bleeding after my regular period was abnormal.

I visited a doctor, who prescribed a two-day medication to stop the bleeding. If the bleeding did not stop, she instructed me to start taking birth control pills. Since the bleeding did not stop, I began taking the birth control pill, which finally halted the bleeding. Seven years later I finished the course on birth control pills. However, again I experienced cramps and passed a golf ball-sized blood clot. At this point, I can sense that this is not typical menstrual bleeding due to the difference in color, light and watery consistency, and heavy flow. I am uncertain about the changes my body is going through. I would greatly appreciate your advice and assistance. Thank you.