Suggest Treatment For Eating Disorder

Is this going to become a full blown eating disorder and should I tell my doctor? I m 17 years old and about 5 3-5 5 and quite fat, about 140 pounds I admit I have anorexic tendencies. For days I would starve until it hurt and eat less (about 500 calories and under) when I decided to. Sometimes I would eat normally until this feeling took hold of me and I start repeating again but maybe for longer. However some of the weight would barely shift and I will start eating again but not as much like before. I take ephedrine tablets to aid with the weight loss and constantly see myself as fat. I m thinking that when I go to the doctor I should tell her whats going on because no one knows except my twin and she hasn t told anyone. My mom doesn t know either. I feel like I want to tell her but I don t because she ll make me stop and I secretly love the feeling of doing this to myself, sometimes I smile just thinking about what I m doing and going to achieve. I also tend to go on pro-ana sites to make me feel better about what I m doing. And for some strange reason I want to be extremely skinny when I do go to see her (doctor) so that when she sees me I ll be nice and thin. I really don t know what s going on. Can someone give me an insight into what I m doing to myself and maybe if there s a name for it since its not anorexia and if I should speak to my doctor. All answers greatly appreciated.