I didn't have a period for 12 months whilst in the Navy. I wasn't on the pill (can't stand those things, they make me sick ). It was pure stress that stopped them. The stress actually caused my estrogen levels to drop really low... about down to the levels that are found in a post-menopausal woman
After about 8 months of complaining to the medics, they finally sent me off to see a gynacologist (a really good one too!) and he figured the whole thing out. He didn't seem too concerned by the length of time that I had gone without a period. I was a bit worried that it could be unhealthy, but he wasn't concerned.
And you want to know what happened exactly a month after handing in my resignation? Guess