Starting Period

So, I went into preterm labor back in April. MY period started back the following month. I have regular periods unless I'm stressed and then it might skip a month. Well, a few months ago it just stopped out of no where. Negative pregnancy tests and everything else looks normal. Doctor refuses to do a pelvic exam but gave me Provera to take. Has anyone taken Provera? Experiances, side effects, pregnancy after. Any feed back would be greatly appreciated.