I too have been of petite stature my entire life. I am now almost 32 and was just diagnosed last year as anorexic and I have not lost my period. In the new DSM, I believe, they have taken out the loss of period part for diagnosis. It is very hard to keep the weight on, especially if you over exercise. Who diagnosed you and did/are they send/ing you to a dietician? Since we can't mention numbers, it is hard to know what exactly you are doing to your body. Coming from someone who used to eat only a child's portion of dinner, I have found out that is not enough calories to keep me going throughout the day. I get to the point where I literally sleep all day because I have no energy to get out of bed. The damage I have done is: I am frequently constipated, My liver doesn't metabolize things correctly, my heart always seems to be racing, I am dehydrated a lot. I am sure there are other things that I cannot remember. Being anorexic sucks the life out of you literally. Don't be afraid to get help while you can. I knew that I had disordered eating when I was a freshman in high school, but was afraid to talk to anybody. I was the "Perfect" daughter and nothing could be wrong with me. I struggled for 16 yrs before I got help. I'm not saying that getting help is going to make the struggle go away, but it makes it a tad bit easier to deal with when you have a treatment team on your side. Feel free to pm me anytime you want to talk.