You mentioned that you don’t feel bloated, but just look bloated, right? Could it be a “food baby,” since you’re so thin? A friend of mine is around 6’0 or 6’1″ and weighs MAYBE 140-145 lbs (he’s always naturally been really skinny). When he would eat meals, especially bigger meals, the size of his stomach would be noticeably different for a few hours, just from the bulk of the food sitting in him.
Just a thought. Pretty much everyone on this diet gets bloated at least sometimes, but when I’m bloated, I definitely feel like I am.