Anorexia or nah?

I'm 15 years and a month old. I am 91 pounds and 5 foot 3 inches tall. My bmi is 16.1. I know it's underweight but I just don't want to gain weight. I also don't want to lose any more weight as I'm scared of being diagnosed with anorexia. I've always been on the thinner side, 3 years ago my Bmi was 18.5 and it's been getting lower ever since. It may be due to the fact I have been skipping lunch at school since last year, but that's because I generally don't feel hungry and would rather use my lunch for revision. I've been on a couple of websites suggesting I'm anorexic but I don't think I am. I don't have a an obsession with my weight because I feel satisfied with it. But my results say otherwise apparently. I guess I'm just wondering if I would be classed as anorexic or not and for ur opinions.
Anorexia or nah?
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