Hi there,
I completely sympathise and feel your pain; I too am 23, and have had a very similar experience! I first went to my GP aged 18 and was put on Microgynon, on that I had "normal" withdrawal periods. They also did hormone tests and uterus scan and found everything was normal so told me to carry on with the pill until I wanted to conceive. Since then, I have been on and off the pill and have only ever had 2 natural periods; 1 in 2008 and 1 a year ago. I have now been off the pill since Christmas and have not had a period since. I went back to a GP and specialist this year because I really want to sort the problem, but just heard today again he advises doing nothing as tests are normal apart from low BMI (about 18.7). This is devastating for me as I find it very difficult to be sexually aroused and when I have tried to have sex it has been extremely painful-I am sure there must be hormonal imbalance and am desperate to sort it out; I also have very small breasts and self-confidence in my body is terrible. I don't feel able to discuss this with my mother or friends either! Sorry to be so negative but hope it helps to know someone else feeling the same. Can I ask whether you have ever had any problems with sexual arousal too?