It breaks my heart to read about Jiggly - this is one dog that you wouldn't mind getting up on the sofa or even being a little naughty - just can't imagine what has happened to make her so mistrusting, sadder still to think what her pups might be like.
My first cat Tintin was very similar in that she couldn't trust people and it took a very long time before she would let anyone touch her. She was a 6 month old cat at the rescue that no-one wanted and hissed at anyone that came near her. Her first step was also sitting on the sofa next to you, but you couldn't touch her even though it was so tempting. Now she's referred to as Nanny Tintin as she has the habit of mothering and grooming every other pet in the house. Now she loves attention be it human or hound. Every now and then she does revert back to her scared self, hissing at people when she's surprised but she is soon back to loving her cuddles. Just needs someone with the time and patience.