It took my best friend about 14 months before her hormone levels went back to normal after discontinuing the pill (she was on it for around 10 or so years). She had gone to her doctor and had everything checked out and she was fine otherwise, and took a number of pregnancy test and they all came back negative.
If you're worried, I'd go see your doc to perhaps put your mind at ease, but you probably have nothing to worry about! I've never had a regular menstrual cycle (I can go up to 6 months without having one) without taking the pill, and I'm healthy as a horse, so just because you're not having a period doesn't mean there's something wrong with you