I promise you that you don't want an eating disorder! An eating disorder is where you believe that you are fat. It controls your life to a point where you think of nothing but food. You can't think of anything else, not your friends, your family and your perspective of what is important to you becomes warped.
What you need to work out is your BMI healthy, and if so - then you are not fat. If you want to gain some self confidence, losing a bit of weight by increasing how much exercise you do and cut back on the junk food will go a long way.
Please don't think that becoming anorexic will solve your problems, as it really won't.