Yay for bowel movement loll! Glad everything went well & she got treated by a very good vet.
As for feeding the right amount, you need to calculate the amount from her ideal weight. If Vet wants her to be around 7-8#'s, then you'll feed her the amount recommended for a 7-8# pup. You might want to upgrade to a better premium brand of kibble, you won't need to feed her as much & it might help her anal glands too...just a suggestion.