As a proponent of The Dog Whisperer's philosophies (works for us, anyway), the first thing you need to do is establish yourself as the "pack leader" around the home. For Groucho, something as simple as not letting him jump up on me made an immediate, BIG difference: by stopping this, I let him know that he didn't have the right to invade my space, that I would not be submissive to him.
Work on gaining control at home (that might include NOT letting her steal socks; basically anything that lets her think she can claim things from you). As she comes to recognize you as "the boss", she'll realize that protecting your pack when you're out is YOUR job, not hers.
It's important that you not baby her - this particularly includes not scooping her up and coddling her when she freaks out. When you do that, you're reinforcing that behaviour.
When we first got Daisy, she had been returned because of this type of behaviour around the home: she'd been the alpha in her litter, and her first adoptive family babied her and let her take over the house... which culminated in her nipping one of the kids for petting one of the other dogs in the house. The day we took her for fostering, we took her straight to the small-dog park, where she spent the whole time with her tail under and hiding between our feet, begging to be picked up. We refused and forced her to deal with other dogs on her own level... three straight days of this, and while she still kept close, her tail was up and she wasn't begging to be picked up. We took he back by the store and they told us she didn't even seem like the same dog, the change was that profound... just by letting her BE a dog.
I'd suggest watching (or re-watching) Dog Whisperer, especially if there are any episodes that pertain to this behaviour... but most importantly, PAY ATTENTION not just what WHAT he does, but WHY he handles a specific dog the way he does (as he says, a big part of his job is to TRAIN PEOPLE).
And if you want to have her evaluated by a trainer, I'd suggest Desiree at In The Dog House (
In the Doghouse: Canine Training and Behavior Inc.)
(edit: Lucy sure is adorable!)