Very interesting. I met a guy who was cutting himself because the pain made him feel alive and it shut out everything else. I told him, you need pain? Come join me for a run and push yourself hard, that way you get the best of both worlds.
I was your height/weight first year in college (about 48 kg), that wasn't by design, I ate a lot but couldn't keep it on easily and running compounded that fact. The most vocal critics of my weight have always been the sedentary office workers who walk around with hip and knee replacements because they never exercise and are either overweight or obese.
Sounds to me like you need a form of continuous escapism, running won't solve it as you can't do it 24/7. I've always been fixated on weight as well but only from a performance issue, also think it is healthier in the long run. Bodybuilders and bulkier people are always in danger of getting obese, in other words once they commit to being that big it's really hard to shrink later. My ideal concept is someone thin and very strong with great endurance. Like Nepalese Sherpas who can carry incredible weights and are tireless.
What professional athlete embodies the form that you want to achieve? What are you so fixated on the quantity of food intake? I get quality, we all can improve on that, but if you at optimum weight for distance running (do you even know what that is, or just don't bother?) why does that matter? There's a point too that skinny gets ugly. I admire Konstanze Klosterhalfen and she has a great physique for running, watching her is like the proverbial poetry in motion. She is unique though, I don't any other runners with BMI that can perform like that.
Also this constant worrying about how others think about you, who cares? Unless it's everyone and impacting your career, then you have a problem but it doesn't sound like it.
Last comment, are your entire life interests centered just on running and eating? No offense but maybe broaden your horizons a little? There is so much out there. I'm obsessed with running but in a way I have to be to maintain my health/fitness, other then that I constantly pursue new interests. The moment you stop reinventing yourself you are dying inside, I've seen a lot of office workers who retire and pass away in a few years or just rot inside. They defined their life by the career (nothing wrong with that but then don't retire) and had nothing to fall back on.