What do you think?

Im a 21 year old female with PCOS. Ive always had issues with my period and PCOS has just made it worse. Each period I get is never the same and the bad ones just feel like they are getting worse over time. This morning I was getting ready for work and its day 2 of my period, which i usually expect it to be super heavy on day 2, 3, and 4. Today i noticed a giant blood clot almost the size of my fist which I’ve never had before. I called off of work and scheduled a drs appointment to be seen immediately as i felt that it wasn’t severe enough to go to the emergency room. When i arrived to the appointment i explained what i was feeling and the concern for the blood clots as even after that i was passing a decent bit of clots. The doctor basically just told me that they are not concerned and to monitor it and if it gets worse I should consider birth control. I left this appointment in tears as i felt i was overlooked and dismissed. They recommended I schedule an appointment with OBGYN (which was completely booked and i just scheduled an appointment with family medicine for today so I could be seen). What do you think? Is this something that is overlooked and I should continue looking into? Has anyone else had this issue, what causes massive blood clots?