Hi there,
Did you end up getting your uvb changed?
That's great that you have a digital with probe end when you place the probe on his basking area under his light, what does it read? I only ask for clarification because you gave quite a wide range earlier and it really shouldn't have that big of a temp difference.
Since you've had him for 2 months already, he really should have grown more with you. What do you typically feed him and how often. Or has he never been a good eater? Babies should be getting live food 2 or 3 times a day, and allowed to eat as much as they want in each of those feedings. This can easily equal up to and over 30 crickets a day. It's not uncommon for them to eat double that at times.
If your temps are good, and your uv light is good, he should regain his appetite and start eating for you. From there things should get better.
But the most important thing now is nailing down your husbandry, and getting him eating.
-Brandon