Ok. The reason I ask is that many new keepers unknowingly underfeed their snakes. And will often ask "where is the poop?". And it turns out there's no poop because the snake is using 100% of the prey item to sustain growth. This doesn't seem the case in your situation.
Soooo, my next guess would be she may be coming up on a shed. They will often times "hold it" if a shed is coming. They will hang onto all the resources in their body to aid with the shed. Typically there is a poop along with the shed when this happens.