I have not experienced this myself, but I have heard of a lot of people with this who do not have PCOS. I don't know your age but it seems common with women who are premenopausal. Some wind up getting a hysterectomy, some it eventually just goes away. Sorry you are going through this. Sounds miserable.

For my PCOS they weren’t “bad” per se. I didn’t notice something was wrong until a cyst burst. But since it made me have a hormone in-balance I use the Depo birth control shot and I’m going on month 9 with no period. I suggest it if it might help with the periods!

Im sorry you're going through that. It's hard enough to deal with PCOS or heavy periods, but to have it last that long is brutal. I had similar problems. Other than my age, (mid-40's, peri-menopausal), I never figured out a definite cause. But, I'm curious, have you recently started a new medication? My sister went through this with her seizure meds. It is rare, but some medications (particularly ones used for migraine s, seizures, or mental health) can cause this.