Size of my guy, feeding and his enclosure

Ember is 8 months old and a hypo orange male. He is our first bearded dragon so tried to research a lot and give him the best care. We currently have him in a 36x24x18 glass enclosure. My question is, he seems really big to us considering he is only 8 months old. He is 21 inches long and 503 grams. He was mostly eating crickets, greens and occasionally phoenix worms. When he was about 6 months old he chose to eat one larger protein meal about once a day, sometimes he would skip both feed offerings in a day. We always offer twice, but if he has eaten a large protein meal for the prior offering, he will only want greens. He doesn't seem like an overeater, but should I be concerned? Is he just moving into adult size and behavior really early and this will be what he is moving forward? Or will he be a massive adult? We recently started Dubias and he loves them (still only wants one meal a day with them), I stop after 40 1 inch Dubias because I am worried he will overeat. Are Dubias like a wax worm and he can get so into them he won't eat anything else?

Also, is his enclosure too small? I am not sure we have the room for anything bigger, but if he needs it we can figure something out.

Thank you in advance!

I would upgrade him to a 4x2x2 tank ---- and I would quit feeding 40 dubias a day -- its the too much protein that leads to gout---------------- you need to feed more salads and offer him worms like super worms and I would only feed 1-3 of those some horn worms 1-2 meal worms 1-3 of those maybe get him some silk worms they are another staple feeder and I think a little less protein content -- if your going to feed him 2 times per day--- salad ----- I would be getting him out of his tank and let him run your LR for 2 hrs for exercise -- he may keep growing I am not sure -- he is big for a 8 month old dragon --
Karrie

The enclosure is a bit small. You should upgrade to something larger. Like karrie said, 40 dubias daily is way too much protein. Too much of any good thing is bad. At that size assorted salad offerings should be the primary feedings with insects being supplemental. Try adding a few worms in the salad to entice eating the salad but just a couple. That much protein will lead to deficiencies obesity and renal failure eventually. Feed insects every few days.