I starved myself being slightly older than you are and normal weight. Now I cannot shed excess weight and my endocrinologist says that part of the reason is that starvation, back then. When your body goes through starvation, be it famine or self-starvation, it would later hold on to every calorie, making it really, really hard to lose weight. The bottom line? If you want to be skinny, you should immediately start eating normally and never go back to starving yourself again. If you cannot eat normally by yourself, you need immediate professional attention.