The only concern I would have before trying to offer too much more is if the baby has pooped. You wouldn't want to fill them up too much and run the risk of a regurge if there's a bit too much going on there.
However, those mice sound very tiny! Fuzzy sized even. Which yes, would be too small for a baby of your snake's size. While the two of them do add up to about the 15 grams of meal, I would personally try a single small adult mouse of 14-17 or so grams for a meal or two before trying the switch to rat fuzzies. Again, trying to avoid regurge is the main concern. And sometimes you get a fussy baby who can be picky about the smell of rats. I have one that way right now. took a couple of mouse scented rats before she got the idea that she could eat them.
Hopefully you'll get a few other opinions on this post soon tho!