[SamiNFurbabies]

That is very kind of you to rescue this little one. You are not alone.

My Izze is an 8 y/o abused rescue that I took in this March. She was very much like your baby. I don't raise my voice with her... otherwise she would crouch....
I keep a strict schedule and take them out every 2 hours and immediately after eating. That seems to help. There are still some accidents, but not nearly as many.
She seems to do better with positive reinforcement, such as getting a treat to go out---that motivates her.
In time, you'll gain her trust. Izze no longer cowers---in fact, she is defiant and has a bit of an attitude. It'll come in time!
Glad to know that your pug likes his new yorkie sis!