What Is The Treatment For Irregular Periods?

I'm 24 unmarried and started having periods when I was 13. Since then, I always had irregular periods. I recently consulted a Doctor & since all my blood tests and pelvic ultrasound were normal,she prescribed me this Diane-35 pills. I never had these pills before. I took those pills regularly for 9 months and had normal periods though quite light.
But its been 4 months that i have stopped taking those pills and still haven\'t started my periods.I\'m so worried.

Please suggest if this normal?Will I ever be able to have normal regular periods?Will there be some problem in getting pregnant?