I'm sorry you had to wait so long for an answer.
I would definitely keep giving her the Bach Flower remedies, and you could also try the homeopathic remedy Gelsemium. Sometimes homeopathic remedies, I find, work very well, and sometimes they don't seem to help. But it's worth a shot.
A year is a long time for her to be holding on to her fears and insecurities. I understand she has had some traumatic history, but it must have sunk in for her that her life now is safe and trust-worthy.
I have never dealt with this problem, so am just able to come up with a few suggestions, as I have no real experience of dealing with this kind of fear.
I think for this to go on so long, then somewhere along the line she must be getting signals that her fear is endorsed by you. (absolutely no criticism implied there....this is so easy for everyone to do!) We as caring sympathetic Humans, see fear, and immediately give attention, to try and comfort or help alleviate the fear. That is natural for us, and would work with another Human Being!
Strangely -not so with dogs! They get any attention or affection -they see it as "endorsement" of a particular behaviour. To them, we are effctively saying "Yes, that's the right way to be" when we comfort or cuddle them when they are having a bad time. It's a form of reward.
So -the best thing to do is carefully watch her for signs she relaxes, and ALWAYS reward -without fail- when you notice those signs. How is she with the sound of human voices....the tv or radio for example?
Get a friend (a calm kind of person if you know one) to come over and spend the day with you all. And to pay your dog no attention at all. Keep a watch -without making it obvious to your dog you are staring at her -for ANY signs of relaxing. Immediately reward her in a calm but endorsing way when you see anything like this.
Try to do that a few times, then maybe you can progress to the visitor offering a small treat ?? (at the right moment)
It might take a long time to get right. Anyway those are just a couple of suggestions of mine. I hope someone else has some more good ideas.
Thanks so much for your comments. So it's best not to talk her down when she's frightened, only reward her when she's calm. I will definitely try that.
I will see about getting Gelsemium for her. Thanks for your suggestions. I will keep you posted!