congrats on getting back to throwing from the mound. my son had tj 7/06. it takes some time to get the feel back, some say a whole season. but it takes pitching to get it back, just don't go crazy be patient. it took awhile for your son to get this far, don't rush this part.
his velocity was back before the feel was. then there can be some confidence issues as well. though not everybody has this issue. but if you do, i think it's the hardest to overcome.
it's good to be throwing pain free, isn't it?
good luck to your son.