My Damaged Dog; Chihuahua

I have a Chihuahua who pancakes when I reach for her. Usually pancaking (flattening themselves to the floor) is a sign the dog was abused. I already knew that, but when I pick her up she's trembling. Which leads me to believe someone picked her up and hurt her. Threw her? Beat her? I'll never know what happened to this tiny dog before she came into my house as a foster at age nine, but in the almost two years she's been here, this pancaking behavior is still there when I reach for her. She was 9 when rescued from a life of neglect in a Tennessee hoarding situation. Skinny, shaking, scared. :(

She's a gentle little yapper. More cuddly every day. She used to stand stiffly when I'd pet her. Eventually, I'd move her onto my lap and she'd still be stiff and refused to sit down. She'd come to be petted, but didn't have the trust in her to sit. She was ready to bolt at any moment. It took over a year for her to sit and relax in my lap. Now she'll jump in my lap and curl up to be loved.

She hates company, but luckily we have a quiet house. Just me, hubby, a 10 year old puppy mill Shih Tzu and 20 year old cat. If someone does come over she'll bark at them from the time they come in until they leave. We're working on this issue. At first I'd let the people drop food for her and she'd calm down enough to eat, then resume her barking. After she'd been with us a year, had her spot on the family room couch, dog bed in the front room she claimed as her own, we moved onto shaking pennies in a water bottle. She was startled at first, but soon realized it  meant knock-it-off. She'll quiet for a while and restart. We're working on this issue.

She came to me with the name Corona and I wanted to change it to something ...more gentle, sweeter, but so far nothing's sticking.

I can't change what happen to her and try hard not to dwell on the hate I can feel for those who did this to such a tiny and loving dog. I wish them karma. Let the universe take care of them.

Moving forward I'm open to any suggestions for her barking at anyone who comes into our house. Its incredibly annoying! Although I understand she spent the first 9 years of her life living in fear, I feel there must be a way to let her know no one is going to hurt her now. Ideas?