If a young beardie (hatchling or juvenile) isn't getting sufficient insect protein and fats and dietary calcium it will fail to thrive and will not grow as fast as it should.
How often do you weigh your little beardie ? (I suggest weekly and creating a chart)
Usual reasons for a little beardie (or any other lizard) not to grow / thrive are :
---- sharing tank with sibling or other lizard who is larger and a more voracious eater (domination) << not the case here
---- other stressors (another animal lurking where it can see / smell it , scaring it) << possible factor
---- handling too often << maybe
---- poor quality food or inadequate amounts of food to meet it's growth and development needs (malnutrition) << is happening here
---- environmental too hot << suggest recheck temperature
---- ----------------- too cold << see above
---- -------------- - inadequate exposure to UVA (required to create a strong appetite) << see *
---- --------------- - inadequate exposure to UVB (need to metabolise dietary calcium) << see *
---- inadequate length of artificial day << recommend 14-15 hours per day.
---- sick beardie (vet visit needed).
It might be an idea to get hold of some HERPABOOST , CALCIVET and a proper feeding syringe and large bore crop needle (with which to get the supplement into beardie's mouth)
see
http://vetafarm.com.au/product/herpaboost/
see
http://vetafarm.com.au/product/calcivet/ , I've used this very successfully with injuried / sick rescued wild lizards
see
http://vetafarm.com.au/product/reusable-feeding-syringe/
see
http://vetafarm.com.au/product/medication-tube-crop-needle/
or ---- it's bored with usual live insects and has essentially gone on strike
<< try another staple live insect , calcigents (BSF maggots) and silkworms are excellent options as alternatives to crickets and roaches.
<< try handfeeding if TOO LAZY to chase it's bugs
* how far from the 10% UVB tube is the basking spot and is there anything between the tube and the lizard other than air ?