Plan B is horrible to use continuously over and over again. Its an EMERGENCY contraceptive which means for emergency situations not as a substitute to birth control. It can really mess up your cycles and its only 80% effective so the chance of pregnancy is still there. I took the morning after pill the morning after and still got pregnant. Have you taken a pregnancy test because by now you would be showing positive if you were pregnant. Also, contact your doctor and request getting on birth control and possibly see if he can give you anything to jump start your periods.
Use condoms or start birth control. Planned parenthood can even prescribe birth control pills, it's much safer and easier than using Plan B.
Plan B is not meant to be a form of birth control and can be very dangerous, especially taken every month.
A good idea would be to call an OBGYN that is under your insurance. If you don't have insurance it'd be a great idea to go to a local health clinic and speak with someone.