I had always been what they call a good student. In 2011, aged 18, I had two A*s and two As at A-level, various sporting successes and plenty of friends. I was president of more clubs and societies than the school needed. I was going to Cambridge University to study English. By most measures, things were going OK. There was a problem, however – I had also developed an eating disorder. Over the two years before I started university, my…