nellie is about 31 inches long and about 600 grams and i would definitely not offer her a medium rat (i order from rodent pro). i actually ordered a few from them because i thought that she would grow into them by the time i finished the small rats i ordered, but they are still way to big. they are almost twice the size of the small rats. perhaps small where you ordered from is smaller than average. if you still need pics i can take some tonight.