Missing period

Hey girls! I haven't had a period in just over three years. Yeah you read that right. My last period was in August 2014. My periods before that were always irregular, so for the first year I just pinned it on stress. I do have a hypothyroid, but with my meds it should have been back to normal years ago. I have told my doctor but she kind of just brushed it off and so I didn't worry. I'm not taking any sort of birth control ( I'm not sexually active as I am just 16 ) so I'm not sure what's causing my periods to disappear. Ive researched PCOS but I'm not in any pain so I don't think that's it. I'm now on a waiting list to see a new doctor but that might not be for months. Anyone with advice please comment ❤️