HELP! No period on my own for 7 months

So over a year ago (June 2013) I decided to come off of my birth control Ortho Tri-Cyclen after taking it for 4 years so that my body would have a year to come off of the pill and get back to normal before I got married. For the next 8 months, my period continued regularly and stayed on the same schedule I was on when I took the pill. The next two months in a row I skipped my period and had multiple negative pregnancy tests. I went to the doctor and they took a blood test to confirm that I was not pregnant and then prescribed me Provera. I had a period the next month due to Provera (May) but still did not have a period over the next couple of months so they prescribed Provera a second time. I had another period the first week of September from Provera. I have not had a period since. The doctors have done an external and internal ultrasound as well as checked my hormones and cervical lining and everything is normal. What could this be? Has anyone else had this issue? If so, what did you do to get regulated again? Thank you so much!!