You may be hypothyroid and that will cause you to have irregular cycles. My cycle have always been normal (every 28days) until i became hypothyroid due to having my thyroid removed. Now i have irregular cycles(sometimes lasting up to 19days and skipping months at a time). also was told that i am pre-menopausal.
Is TSH the only test that's been done? It's higher than normal, but a thyroid condition can't be diagnosed simply from TSH. You need, also, to get Free T3 and Free T4, in order to actually determine thyroid function.
Do you know if you have Hashimoto's Thyroiditis? That's an autoimmune disease that attacks, and destroys, the thyroid.......
Is this a thyroid question? Do you have a thyroid condition, causing your irregular periods?
If so, what condition do you have? Can you post recent thyroid labs, including reference ranges?