I am in total despair?

The fact that you're suffering is clear, but regardless of that there is much more to life than your bmi and your weight. Honest to god, there are unspoilt people in poor countries who never give a thought to their weight because they're too busy focusing on survival. You put so much emphasis on your weight it's pathetic. I have never had a weight problem in my 48 years, and the only people i know who are overweight, underweight, anorexic or bulimic, are those who go around worrying about it. I know it sounds obvious but fat people are always on a diet. Quit worrying about your weight, it's making you ill. Quit worrying about what you look like. Start focusing on what you can do with your life instead. Honestly, you've put so much importance on your weight that you let it rule your whole life.