Am I anorexic? How much longer can I go on with my lifestyle before I'm hospitalized? Do you have any advice?

I eat 50-400 calories a day, before purging. I hate food and I only eat it when other people make me or when other people are suspicious. I purge about 50% of the food I eat. I know I'm not fat, infact I'm 5' 6" and 105 lbs... Even though I know I'm not anorexic and I don't have a problem, my best friends seems to think I do... I hide my eating habits from everyone. I run about 8 miles a week.