Yeah, that is useless and offensive. There may be nutritionists that can help with how much you eat as well as what you eat, but clearly the one you saw is not one of these.

Eating too much is probably something that a therapist would help with more than a nutritionist. But if you eat because you feel hungry even though you know you're eating enough, possibly a diet change you could try is eating more fat and protein and less carbohydrates. Fat and protein are very filling, so people who go on this sort of diet generally eat less because they feel full on fewer calories. On the other hand, I have no idea if this is something that you can do with the latex fruit allergy since I remember looking at a list of things that you should avoid which included avocados and nuts, which are some of the better vegetarian/vegan fat options. Nutrition is hard.