So I finally got a scale to weigh Donuts with. She's 290 grams, hasn't pooped much since... I can't even remember when. I am pretty sure I was underfeeding her for a very long time ):

Back to the question, what prey size should I offer? I had her on adult mice for a while but I could tell Donuts was not really growing much on them so I switched her to small rats. I would have preferred pups or weaned rats but Petsmart never has them.