Join Date: Nov 2012
Location: Albuquerque, NM
This is kind of a difficult problem to answer online, I think, just because it could be several things. My general advice is to do positive training with her. I like clicker training for fearful dogs, because it is fun and because they have to think and figure things out for themselves but are never punished, only rewarded, it can really boost their confidence. It also will improve your relationship with her and create a bond of trust between you, plus help you learn your dog's body language so you can tell what she likes and what makes her uncomfortable. edit for clarity: I mean you personally do the training, not have your family do it (although that isn't bad). It doesn't even have to be that time-consuming, just 15 minutes a day can help.
Is she only afraid of you when you try to play and make sudden movements, or is she always nervous around you? I have seen some people, mostly men (I'm assuming your sex here based on the wife and kids; forgive me if I'm wrong), who play really aggressively or forcefully with dogs, which can scare more sensitive ones. Pay attention to your body language--are you getting in her face to drop the ball, wrestling with her, etc.? She may just not like to play like that. You may have to learn to back off and play the kind of games she likes.
The rowdy dogs:
Hector-2 y/o GSD (mix?) rescue
Scooter-12 y/o ACD/Border Collie mix
Bandit-8 y/o ACD
Wooby-14 y/o ACD
Abutiu "Abi"-ACD puppy and hopeful future SAR dog!