Need help!!!!!!

Hello everyone!! Me and my husband have been trying for months to get pregnant but nothing has happened so I gave up. This would be our first child. I have gotten tested to see if anything was wrong with me but everything came back good and for him also. The only problem I have is that I don’t have a period every month it comes every three months but sometime it doesn’t come. My doctor tried to put me on birth control to see if it would help but it did no good it has been 2 years since I been off the birth control. Is there anything I can do? Please help me ?