Hello Loulou: I can't tell you whether or not it's likely you have anorexia. But there's something going on here. And as you yourself wrote in your post it's causing you unbearable anxiety. GO SEE A DOCTOR! You might start with your GP. But ultimately see someone who specializes in eating disorders so you can receive a professional assessment. I see you're in the U.K. And I know healthcare services are provided differently there than they are here in the U.S. where I am. But do get in to see someone as soon as possible.

Here's a link to PC's Eating Attitudes Test just in case you haven't already taken it along with a link to DocJohn's article, from PC's archives, on the subject of eating disorders:

Eating Attitudes Test | Psych Central

Eating Disorders: Symptoms, Types & Treatments | Psych Central

My best wishes to you...