hi cillie,
I picked up on three point you may want to consider.
1. at 6 months she should be fed crickets twice a day, and be allowed to eat as many as she wants in 10-15 minutes. dust one feeding with calcium or vitamins everyday. the salad should be available at all times but dont expect her to eat too much because at that age she still needs a good amount of protein. go easy on the mealworms, the chitin exoskeleton is hard to digest on the younger ones.
2. get her off the vita-sand - that stuff is just downright bad. any juvenille dragon should be on non-particulate substrate until at least 10 months. then you may use sand if you wish, but use playsand from Home Depot, not the reptile sands which are overpriced and dangerous - ignore the 'vetinarian approved' crap on the packaging.
3. at 11" she really needs a bigger tank. 10 gal is almost too small for a baby anyhows. by now she should be in a 40 gal breeder or bigger. beardie growth is not stunted by cage size, but it cant help matters either.
her small size is probably due to underfeeding, but dont worry. i was in the very same situation as you about 5 months ago. i upped fuegos feeding and moved her to a larger tank, got her off the walnut bedding and now she's 18" at 11 months. i learnt from my mistakes with help from people here - now its my turn to pay it forward. good luck
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Ross
0.1 Bearded Dragon (Fuego, spent the last 10 months thinking she was a he!)
2.1 Roommates (require more cleaning up after than the dragon)