Help- is my weight unhealthy?

I got diagnosed by my doctor with anorexia but i dont think this is true I hadn't had my period in 5 months but a week later I got it. he also said my weight was dangerously low but i dont think its true im 5 foot 8 and 103 pounds but i want to get to 85 pounds i used to be 96 and loved it. i hate my body because i think im fat and am desperatly trying to lose weight and stuff. im starting therapy but I'm really scared because i really dont think I have a problem, what should i do? and does my weight sounds healthy? thanks for all your answers