Greetings. This is my second post so bear with me if I don't use the Latin Names yet. My wife's bearded was also slow to grow until we put her in this:

It's 48 X 24 X24. Now she has almost tripled in size. Besides the small veggie plate she has about 20 to 30 medium crickets a day fed in doses of about 10 at a time. She will probably need to get get a new driftwood that takes up less space.
My wife's baby.
John