Hi,
It seems that you and I have been on a similar schedule of surgery and treatment. I finished chemo late December, left mastectomy in early August. Being fairly new myself, I don't know that I can be of help in telling you what's going on, but I do know that with this history of pelvic pain, I wouldn't accept the explanation of possibly shrinking ovaries. I would grab a doctor on your oncology team and ask for examination, tests, whatever is needed. This is tough enough without having to worry about this pain.
Best of luck to you and I hope you get some answers.
Janie