Young snakes eating baby rodents tend to digest them easily, meaning they digest quickly. Not living with your snake but if it really seems excessive defecation, you
might also have her stool checked for parasites. Captive-bred snakes shouldn't have any, but they can get them from unclean prey sources if & when fed live, & if that's
the case, it's easily taken care of & should be, so her growth isn't adversely affected. All may be completely normal, just suggesting another possibility to keep in mind.
I've actually seen a w/c adult snake that was so encumbered with 'worms' that he digested a large adult mouse in roughly one day, because he had so much 'help'.But hopefully that's not the case here, just sharing where my perspective comes from. It's not likely to be the issue with yours.