I had the same problem. Was put on BC pills when I was 15. Stayed on them till I was around 17. When I quit taking them, I had no period for around 5 months. I gained weight, face broke out, felt like I was going to explode! Went back on the pill & took them until I considered getting pregnant at 28. But again ... no period. Went back on & off & finally had my first child at 31.
My niece has the same problem (she's 20). What does your doc say? I finally got all straightened out ... NOW perimenopause & I'm all screwed up again. Sheesh!
Good luck sweets!