Anyone who has had a truly traumatized puppy mill dog knows how long it takes to rehab them. They are not the typical rescue pup.

I cannot stress this enough....but to the OP: You can try anything, but my suggestion is the if things really make her retreat, let her retreat! Pushing things on her will only serve to make things worse. Just MY humble opinion. I am not here to argue with anyone...I am only here to share my experience and I do have experience with many rescue pups...both the ones who have come from homes and have come from mills. Trust me there is a HUGE difference in them.

Links to read about rehabbing a mill pup:

Please note that they all stress patience and letting the pup set the pace. Otherwise, you can do more damage and things go backward instead of forward.

Adopting a puppy mill dog can be challenging but rewarding

Working with Puppy Mill Dogs

Caring for a Rescued Puppy Mill Breeding Dog speakingforspot.com
A quote from the above link that is true: -Enter the process with realistic expectations. Understand that your rescued dog may not ever be a “normal” pet in terms of her trainability and responses to new people, other animals, places, and things.

I agree with Linda and as I said in my initial post - these dogs can have fragile times ahead during rehab and afterward and need a safe place to run to. That's why I suggested in that same post providing the den, a place of retreat for times of panic but don't stop working with her, once that panicky spell is over. Later that day or the next day, pick right up and proceed on schedule. I've rehabbed many very troubled, starved/sick/injured dogs by allowing them their time to settle in for a month or two, giving them scheduled work to do, which to a dog, they see as fun, and a place to go hide away when regression happened - and it will. But you don't dwell on it, just keep slowly moving forward as the dog's psyche allows and he'll strive for better. They want to get better and be happy, they just don't know how to do it.

Your baby sounds so much like Tibbe's first 6 mos. it's not funny. According to the lady he was dumped on and who I got him from, he was raised in puppy-mill conditions by being kept his whole life in one cage in a shed with other dogs in their cages with no vetting or socialization and the poorest of poor quality of food. His retained baby teeth and his permanent teeth were brown from his poor nutrition, his vets said. He was flea and tick ridden, dirty, matted and traumatized to the max from being stuck in a cage and apparently felt he couldn't flee when thunderstorms or other loud noises scared him - he was just stuck in that crate and never got out and apparently he felt powerless. Noises were his big bugaboo. Everything that made noise scared him silly to panic level. It took us twenty months to two years to finally get him to a peaceful, happy, feisty place of self-confidence and really enjoying all spheres of his life but now he lives large and enjoys life. He regresses a time or two a year but quickly comes out of it by giving him his space, his den and in a half hour or so, a suggested car ride, tugowar or walkies or training and he may or not be ready to come out of it - sometimes it's up to two hours before he's himself again but then, he's back and happy to go at life again.

I've had much worse dogs than him, true curs even, living in corners of their crate or flat to the floor for the first month, but basically, though their bounce-back times varied when they had panic attacks after rehab was started, it was the same story once the dog had been gently and lovingly rehabbed over time with consistent work/game/play schedules they came to count on, praise and cuddle sessions throughout the day and evenings on the couch with me watching TV, sleeping with me, and together with the slow desensitization sessions and life enrichment games and puzzles we'd work at, they were different dogs afterward. But a dog that has had serious fear and panic issues will usually always have them a few times a year but those times can be overcome and life can go on.