Well, you definitely aren't starving him by feeding him smalls, but maybe you could step up to large smalls? or small mediums? Feeding him 2 smalls is pretty useless because he's eating so much extra fur and stuff he doesn't need more of.
So what size enclosure are you planning? That would be really cool - when I get a house I'd like to get a burm. Or maybe a retic. Something I can set up a bedroom for.