i dont think youve stunted there growth. im not an expert, but iv had mine for around 5 years and besides last years unexpected first winter fasting, everythings been going great.
for a 27 inch ball 1 mouse a week is far from underfeeding. when mine was that long i fed her either one or two mice per week, and occasionally a rat that wasnt much bigger than a big adult mouse, just cause the feeders around here are usually half as big as a mouse can actually get.
but if i were you i wouldnt worry. i dont think that it would hurt your snake to feed it two mice a week if it would take it, but i also doubt it would hurt it to just do like youve been doing and feed it one. some balls will only take one mouse a week, i know someone whos got a 3 foot one that only takes one a week. i recomended he try and feed it two, and it ate one and ignored the rest. it wouldnt even take small rats.
so dont stress it. sometimes with balls your lucky if they eat at all, then some will eat like 5 a week.
i very with mine. shes around 3.8 or nine and il give it between one and three a feeding, and sometimes il give it two small feedings a week of one or two. iv given her hamsters, gerbils, rats, even chicks just for variety. i give my lizards a variety, so i dont think its bad for a snake as long as it gets what it needs, not too much or too little. iv only got the one snake in a big tank, im no breeder and i dont have a fancy rack or anything so i dont just throw a frozen/thawed in there once a week. i like to watch her kill the furry little childrens pets, and to make sure they dont bite her im prepared with the tongs to make sure they bite the tongs if they have to bite anything. sorry for the long post, iv just drank alot of coffee, and i dont mean to criticize breeders and there fancy racks, know that im jealous and would love to give my snake some booty and make some great pet snakes. also if you like goregrind and grindcore check out gigantic brain, thats some really awesome grindcore. later