Yeah, that would explain it, at his age he should be closer 3,5-4"
assuming everything else is correct in husbandry you need to change his diet completely. Crickets especially canned ones are not the best to say the least.
you need to get multivitamin powder, use it once a week, ca/vitd3 use every second feeding, but not on a same day, get nightcrawlers ( fishing stores), hornworms, feed that instead of your crickets and zoomed food. Use as much variety as it is available, give him pinky, waxworms, butterworms, roaches, anything that doesnt contain lots of chitin (mealworms, superworms). Your goal is to feed him as much as he can eat every day until he is normal fat guy

after you will need to control fat containing feeders and give mice no more then once a month and forget about waxworms completely
he is young, with proper feeding and supplements he should be just fine.