Super long period?

Hi ladies...I have PCOS which causes a very irregular cycle. I would only ever cycle like once every 4-5 months. Lately it has become more regular, than shortened to a cycle of about 3 weeks!
​ period started 17 days ago, very light, some days just spotting, then in the last week it's gotten very heavy and it just isn't stopping! 17 days is too long for a period, right? What's happening to me?!!