My cat broke her pelvis about 18mths ago, and this thread has brought all the memories.
Whispa also to start with would try to sleep in her litter tray, I think she was trying to be clean but moving hurt so she thought she would just stay there. She would also occasionally as she was getting better move herself into a position that hurt, so she scared us occasionally with some sudden whimpers.
She improved alot over the first couple of weeks, then the problem was trying to stop her jumping about.
She has since made a full recovery, well apart from a slight limp and a little stiffness after sleeping. She is also happy to be in the house a lot more.

I am so pleased for you both that she is now home and on the mend.

__________________
Steve & Karen

Smudge - Border Collie
Whispa - Tabby Cat
Magic - Black Cat
Chickens