At first hognose have a very slow growth simply because what they eat is just a mass of water and fat (no, bone, no fur, little to no protein) and to add to that they defecate a lot, every 3 days is a pretty standard schedule for an hatchling that's what I feed mine.
Give it time you really start seeing growth when they start eating fuzzies.
Right now I can tell you that last years babies I currently have are from 12 to 18 grams so not much bigger than yours.
would it be possible to feed 2 pinks every 5-7 days?