11" long at about three months of age is a good size. Again he doesn't look over weight in either of the pictures you have shown.
However, I have some suggestions about his diet. The redleaf lettace, though a bit better than iceberg lettace, shouldn't be a stable green. Collard greens, dandelion greens, endive, escaroli, mustard greens and turnup greens, are more suited for daily salads. It is best to mix two or more of the greens listed above, then add other vegetables etc into the mix. Such as, collard greens, endive, green bell pepper, zuccini, little bit of carrots (or squash), one small strawberry,chopped.
Squash is a good vegetable to give but too much can cause the stools to be runny. I don't know off hand if there is any other negative aspect of feeding too much squash. Use as much variety as you can, not necessarily ever day, but frequently. The way I have done it before was alter the staple greens, or have 3-4 staple greens, plus various vegetables/fruit/edible flowers. A great guide for what foods are good for bearded dragons, what to avoid and quantity to give them on a daily/weekly basis, is the nutrition chart at:
www.beaufituldragons.com
Butterworms are good insects to give dragons, superworms are much better than mealworms but I would keep them moderated which I see you are doing. If you find butterworms starting to be costly, silkworms are good too. They are also almost escape proof and even if one does manage to crawl away from the tub they are stored in, it is not hard to find them. Nor are they any great problem even if it does crawl away and coccoon somewhere. The moths they hatch into are incapable of flight so they are not likely to spread. A variety of insects is good to, so offering butterworms, silkworms, superworms, crickets, roaches etc, is great.
Overall, I think you are feeding at a good rate. Keep up what you are doing, dusting your insects once a day with a multivitamine and calcium powder, if you are not already. When your dragon reachs about 8 months,cut back to one insect feeding a day (lots of salad still of course) and dust once every other day. At 12-14 months, feed insects 2-3 times a week, dust 2-3 times a week, salads every day. Alternatively, for adults, is feed only a few insects daily, no more than 10% of his daily intake of food.
-----
PHLdyPayne