What could help me conceive?

I have regular cycles that run about 30-31 days. My youngest child is 8 years old and after she was born i went on birth control and have been off for about 4-5 years now. Nothing has happened. I just dont kow if im actullay ovulating because you dont have to ovulate tohave a period. My period is only about 3 days long and used to be about 5. I dont know if a supplement could help. Any advice?