Chris,
thank you for giving this girl a good life. It breaks my heart to see them so afraid. And to know that people made her that way.
Dobe's are somewhat more fragile than Rotties but their job, for which they were bred, is similar. They need to be fearless to do it well. Some people think that means they have to be mean and aggressive and that's where the behavioral training gets out of hand.
Hug her for all of us. And tell her that everything is all right.
Jim