I suggest you go back to see your physician. Common causes of amenorrhea are pregnancy, elevated prolactin, anovulation (commonly due to polycystic ovarian syndrome), emotional or physical stressors, uterine adhesions or thryoid abnormalities and other causes.
I suggest you be re-evaluated.
I have irregular periods as well and so does my cousin.
Her's is due to being on birth control pills for 3 years. She got off and was ready to conceive with her Husband but no period. She took a herbal supplement that you can buy at GNC stores called Vitex. She had a period in two months! I just started talking it myself at the begining of this month but haven't had a period. They say it takes up to 3 months to regulate you! If you research about Vitex you will also notice it helped many other women!
i went 5 months without a period when i was 16. i had jsut started having sex with my boyfriend who is now my husband. from jan.-june my AF was abscent. my mom took me to the doctor and they couldn't find out what was wrong with me...no cyst or anything. i took an HPT around the end of june and it was positive...my mom almost flipped out. she took me to another doctore and it was negative......about 2 weeks later i had my AF and i was in so much pain that i didn't go to school for 3 days. haven't had anything like that happen since then....so i still don't know what was wrong with me. best of luck to you!!!!