Hi! I had cysts on a "regular" cycle AND stimulated, in fact looking at back at symptoms in the past I am sure I have had them several times. They can vary in size, and either be hemoragphic cysts, or Corpus Luteam (CL) cysts (I think there may be different "flavors" of CL cysts). At any rate, I have had both and each produced different symptoms, although I think they are interchangeable symptoms. The hemoraghic cyst I had was 3-4cm, but did not produces estrogen nor bleeding. I had no symptoms of it whatsoever, except that when I went in for a baseline, it was there (I wasn't going to be doing a cycle, it was actually during my initial IF workup that they found it!). I was already scheduled for a d&c/lab/polpectomy, so they decided to remove it during that (otherwise, they said they'd normally just let it go away on it's own). The other times, I had CL cysts but they didn't produce estrogen so it didn't hold anything up and I had no symptoms. However, one time time in this last year that I had a cyst, it was more like a CL cyst and I discovered it because AF came on CD 18 or something like that, so I went in for my baseline to start my first IVF cycle, and it was there (no meds in the previous cycle either)! It was only 18mm, but was producing E2!!! My estrogen was around 250. At first, Co - oper thought it was a growing follicle, but in the end it was a left-over CL cyst that was still producing E2 (You could tell based on my BBTs and P4 levels because nothing "happened"). Even though you think you might not have had a cyst over these last years, you may very well have because like I said, I had no symptoms of the hemoragphic cyst, or the non-E2 cysts, but I did for the CL cyst. (well, the only "symptom" realy was early AF, but I didn't have much pain or anything like that, very mild).
As for your thoughts on cancer, I think about this ALL THE TIME and it scares/freaks me too! I am more scared about OC than BC, simply becasue in my experience doctors pay more attention to that and will foo-foo OC testing (which I understand some of the testing might not be as developed as for BC). In fact, I had some weird pains a few years back and had to beg and plead to have them do more testing to rule out OC. NOw, I know it's very rare, but I personally know 2 people, one is in our family, that had/have it and they said to be persistent with testing if you have concerns.
Good luck with dx the type of cyst you have! Let us know how it goes