Yeah, I typically try to feed rats as well. From what I know, rats have more protein while mice have more fat, so generally the rats are the better option. Since she's been on live beforehand it does make sense to try to stick with that until she's more settled in, just stinks that your local store doesn't have anything in the right size for rats. Depending on where you live, it might be worth posting an ad on Craigslist or something similar to see if there are any local feeder breeders that might have something closer to what you're looking for. Worst case, you could order some f/t and if you haven't found a better solution by Sunday offer her one in case she decides to not be picky. Since you're planning to switch to f/t eventually anyways, it wouldn't hurt to order them a bit earlier than needed.