Suggest Treatment For Infertility

hi mam,
i am from kerala i am 22year old and was married.we have no child till 9 months.when i went an hospital they check me and result was normal.but my menustral was not normal. if 2 months period then on 3 month it won't be.i was period on 25 dec,24 jan , 22 feb but on march still perid has not come. i test with pregnecy card but it was negative plz mam suggest me something