My cham is also about 7 months old, and he's literally only down to 1-2 hornworms (fairly large) or 1-2 medium-large dubias per day. They're extremely filling though so I understand why, plus the dubias I feed him are well gutloaded + over an inch each. They're much bigger than what ones he was on a month prior lol. However he'll eat unlimited amounts of mealworms if I let him, or around 7-10 crickets, so I guess the dubias/hornworms = roughly that amount since he's full after one usually.
He's not thin by any means, and looks quite healthy but I've been wondering this very thing too! He even has days where he just doesn't want to eat, but then will have a great appetite the following day. I basically just will feed him as much as he's willing to eat, minus the mealworms (only give him like 5 max couple times a week).
What sizes are the dubia's ? Are they smaller mediums? Just curious to see if ours both eat similar amounts or not! Your little guy is gorgeous btw, he and my Felix look very much alike!!