I too have a puppy mill rescue and Ivy used to go in her crate too. I also put her in my bathroom as I thought she would be better in their (tile floor) OMG the mess
Ivy is about 5 or 6 years old and never house broke. I then took her out side to go pee and made everyone say the same word (pee, pee) When she would go (I also always had her on a leash) I told her she was a GOOD GIRL and gave her a treat. I took her out as often as if she were a puppy. She now is house broke
I think the treat was the thing that works she loves chicken. Just give it time it will work as long as you stay with it. Good luck