Does anyone have any explanation for what’s going on?

TL;DR

Passing large chunks of tissue with no possibility of miscarriage, extremely painful periods and history with reproductive medical problems.

Some medical background I’m on the pill that limits my period to every three months, my family has had a long history with endometriosis and fertility problems, and I’m prone to ovarian cysts and have had to go to the hospital for them.

My past few periods have been extremely painful and I pass these large chunks of tissue as well as a ton of flecks (picture taken in a bath btw). My flow is relatively light to normal though. I don’t think they’re clots but they’re defiantly large enough to be concerning and I can’t find anything on them other than miscarriages which is not possible for me since I’m not sexually active currently. I pass a couple of these per cycle and tons of medium sized ones as well. Anyone have any ideas??