Has anyone experienced endometrial polyps specifically while on the pill?

This has happened to me twice now, and I'm looking for anyone who might have gone through this or might otherwise be able to advise me. I start the pill, and after a few weeks, I start having breakthrough bleeding. After 2 weeks of constant bleeding on the active pills, I go off the pill. The next day, after seriously intense cramps, I p a golf-ball sized polyp. (I know that's what it is because the second time around I had my gyn send it to the lab.) I want to know why the pill might cause this, if a different pill would probably have a different result, and if I'm putting myself in danger not having the endometrial biopsy my gyn offered. (I just can't do that, besides the polyp was benign.) I've been on the pill before with no issues, and I've had two totally normal pregnancies. The brand name of the pill is Levlen. Thanks for any decent input.