Help with irregular period that has been going on for months and months please... help...

I have talked to doctors... all they did was put me on birth control pills... but my period have not still gotten regular... its been going on for years... it stops once in while... but its still going on for months and months... I think I have pretty good eating habits... too... don't over exercise either... don't work toooo hard... what can I do... we are trying to get pregnant... now please.. tell me what can I do... please