I'd personally only feed one rat that size....actually a bit smaller if you have access to them. Make sure your temperatures are spot on and keep feeding every 5-7 days.... they'll get there on there own time...

A jedi once told me that a lot of girls will slow their growth once they hit approx. 1000 grams, and sure enough in my own collection....it took a few of my girls quite some time even with regular feedings to get over that hump....you very well may or may not encounter the same thing with yours.