If your thyroid is being properly regulated, I would ask for sex (ovaries) hormone testing.
You may want to google PCOS.
As an aside: "High prevalence of autoimmune thyroiditis in patients with polycystic ovary syndrome:"
http://www.repromedix.com/pdf/ATA-PCOS.pdf
I would get the tests Ifupleeze mentioned. Also, I had a friend like you and she had to be on b/c to have a period. Her doctor said her hormones were not balanced. I would have some more tests to rule out that and other things. Good luck:)
You might be experiencing adrenal failure. This can cause irregular periods and several symptoms are the same as hypothyroid. Ask your doctor to test for adrenals including DHEA, cortisol and a full metabolic panel.
Do you have any other symptoms besides a abnormal period? HAve you been keeping up with blood tests on you Hypo Dx?
How long have you been off your birth control pill?