I have had the same exact problem my whole life. I actually did not even know I was pregnant w/ my daughter til I was 6 months along because of the lack of periods. I went to my doctor and he did about 12 different blood test and could not find anything wrong w/ me. He finally told me that he believed it was just a vitamin difficency. He told me to start taking prenatal vitamins, as they have everything you need all in one (whether your pregnant or not). I started taking the vitamins and within a month I did have a spotty period for three days. So, the doctor was right. He also said my diet could be effecting my body to the point that I would not have my period. I would suggest you did as I did and try taking some vitamins and change your diet slightly. I bet you will see a difference within a month. If you do not than I suggest going to the doctor because I was told the lack of period could be because of an auto immune disorder. I would try the vitamins first though. I also started having a problem w/ my hair falling out more rapidly after I had my daughter and the vitamins changed that too. The power of a simple vitamin is more than you would think.
Hi, it sounds like you need to go back to the doctors and sort it out. It does seem like it could be hormone problem and you will need to talk it over with you doctor and get some advice to get you back into a proper cycle.