Welcome to the forum, Congratulations on Annie. Sure hope you'll share some pictures of her with us.
Advice, I have lots..... my Bridge girl was a former puppy mill momma. Like Annie, when I got her she was terrified of everything and I mean everything including us. She hid behind the toilet in my bathroom for a week. My husband had to pick her up and carry her outside to go potty because for the first week she was with us, she wouldn't walk let alone come out of the bathroom.
After the first week, she decided to explore the house and she went outside on her own. I would go out with her and let her walk around the yard. I had to work with her for about a week on potty training before she stopped having accidents in the house. After that, I either would take her out or she used the pet door I have and would go out on her own.
Her entire world had been turned upside down..... she spent the first two years of her life in cage that wasn't big enough for her to stand up or turn around in. She'd never touched grass, never been in a car, in the house. She had not been socialized, she had been verbally and physically abused. Because of this she was afraid to be touched, afraid for us to be behind her.
First of all, keep in mind, Annie's entire world has been turned upside down. She is going to need a lot of love and patience from you and your wife. Each dog is different, give her the time and space she needs. She needs time to adjust and relax, she needs time to learn to trust you, once she does, you will see a completely different girl.
It took months for my girl to completely trust us, once she did, she started exploring her new world and gradually with time became a part of our family. I also had a well adjusted Golden boy that was her big brother. He really helped her out a lot and most dogs that have not been socialized, benefit greatly from one that is well adjusted. When my Boy passed, I adopted another young golden boy that was well adjusted to be with her. A lot of puppy mill dogs will always need to be with another dog and my girl for sure was this way.
Be realistic with your expectations with her, be very patient and very consistent. Give her the time she needs. You will probably find what normally works with a well socialized dog may not work with her. Try different things, you will be able to find what works the best with Annie. My girl was not food motivated when I got her, but she responded extremely well to being told what a good girl she was......
I am not going to tell you this is going to be easy, but I will tell you it will be worth all the time you put into her.
DVGRR has a lot of Resources, take advantage of them. There's a Fearfuldogs website and a Fearful Dog FB page. Here's the website, lots of good information on it.
Fearfuldogs.com
There's also a book on Amazon, might be worth the read.
https://www.amazon.com/GUIDE-LIVING...-3432559-2440110?s=books&ie=UTF8&qid=1526496322&sr=1-6&keywords=the+fearful+dog
Amazon has a lot of books about working with Fearful Dogs.
Check with DVGRR to see if they have a trainer that can work with you and Annie or if they recommend one. I'd give Annie time to adjust, settle in, learn to trust you before working with a trainer though.
The best way I can put this, is you need to take Baby steps with her and there will be days you will take 2 steps forward and one backwards...
Just be patient.....
Good luck, hope you'll keep the rest of us posted on her progress and again, would love to see your new girl, so post some pictures.....