I have a 7yr old sulcata from which I heard he is undersized for his age. 12inches and 10lbs. Told he should be way bigger. He lives outside in outdoor inclosure 8ft long 4ft weed with hardware cloth over the top to protect from birds of prey(i live in Fl). I let him from roam the yard with supervison for an 1hr. Bring him in when weather drops with basking area of 80. Any idea why he might be undersized? Thanks