Adopted Suriname boa very small?

[Kashy]

Hi everyone!
I adopted a 2 year old Male Suriname redtail about a month ago from a shelter. When I got him, he was in a bad state, super underfed, and had shed from a few cycles stuck to him. I put him in a new terrarium with a fogger attached to a humidity controller and waited a week before feeding him. Started him off on a small mouse to let him build a bit of gut bacteria and now after a month he's taking an adult mouse with no issues every Sunday. After having his humidity up, his stuck shed got loose enough for me to give him a bath with zilla's shed ease and most of the stuck shed came off by itself after 25 mins and the rest came off as I let him move around between my fingers while in the water. He seems a lot more active and happier now in his enclosure. Having said everything, I still suspect he's very small for a 2 year old boa (I suspect he'sabout 3 to 4 feet but he's very skinny), and I am wondering if there is anything I could do in addition to regular scheduled feedings to help him reach adult size. Will he ever reach his potential size? Thank you!