The pressure you feel to be thin is a major concern. It is driving your obsession with being thin. It is an unhealthy obsession. In your mind, you “need” to do it. You have given yourself no choice. Your ability to limit your weight has become paramount.
In addition, your body, its size and shape, has become your primary vehicle for success in life. A thin body, in your mind, has become the one and only pathway to popularity, attention, belonging, and to professional dancing. It is everything. The pressure you feel to be thin only makes sense in the context that you have placed on the importance of body size.
You wrote that you are desperate. I can understand why. All of your hopes and dreams depend on your ability to limit the size of your body. The idea that being thin is the key to your happiness is an illusion. For those who believe this illusion, no amount of weight loss is ever enough. More is always better even when it isn’t.
This problem is further complicated by the fact that your view of your body is distorted. As you mentioned, you are a “normal” weight but continue to see yourself as “fat.” That one line from your letter to me, shows you are no longer able to see the reality of your appearance. If the scale and the charts show that you are a normal body weight, in the normal range, you can not appear to be fat, not to others, not to trained professionals. You can see yourself looking fat in the mirror but that is an illusion. Almost everyone with an eating disorder sees an illusion staring back at them in the mirror. A fat illusion.
It is important to recognize the incorrectness of your thinking. If it continues, it can lead you down a dangerous road. Some individuals who feel extreme pressure to be thin ultimately develop eating disorders.
My recommendation is to discuss this matter with your parents as soon as possible. Don’t be afraid to ask for help. Ask your parents if they will take you to counseling. Counseling could help you to develop a healthier relationship with your body. It could also help you to manage your weight in a healthy, controlled manner and address your depression and feelings of isolation.
Now is the time to seek help. You may or may not have an eating disorder. Counseling can eliminate the possibility or stop it before the problem becomes unmanageable. The “find help” tab at the top of this page can help you and your parents locate a therapist in your community. Please take care.