Maybe get a crawler, which is right before they are weaned, or if you can find some smaller weaned rats. Either way I don't think the move up in size will be a problem.
Maybe I will pick up some small weaned rats and try that next feeing. She is eating the pups pretty fast now and they are pretty much same thickness as her biggest part of her body.
1.0 Dumeril Boa (Mr. D)
1.0 Red Tail Boa (no name yet)
0.1 Ball Python (Pandora)