Genetically shy dogs are difficult. I just wanted to share a couple of experiences with mine, to help you understand.
I got this dog at 8 weeks of age. The breeder was a friend, and I assisted with the whelping.
When I brought her home, she was fine. We took long walks through town, she kissed babies in strollers and watched heavy equipment at work on the road without turning a hair.
We also took long walks through the bush, and when fall came, she hear the sounds of hunters shooting their deer rifles and wasn't bothered by it in the least.
Then the winter set it. I was in Northern Ontario, and the temps. got to 30 below and sidewalks were like skating rinks. I also had surgery so we did not get out a lot.
When spring came along, we started going for walks again. On one of our first walks through town, a good friend came walking towards us. This was the first person she'd met when I brought her home, other than my two boarders, and she was a fairly frequent visitor at my house.
She freaked out and tried to hide behind me. If she'd been able to slip her collar off, she would have run home.
After that, we made frequent trips to the center of town. We'd sit on a bench, and watch the world go by. One of our favourite places was a coffee shop with outdoor tables. We made it a regular stop, but when people came by she would hide under the table and not let them pet her. I told them to ignore her.
One day, she let a lady give her some treats. A few days later, we met the same woman on the street, and of course, she wanted to pet her. Teena nearly bolted for home, and even though her fear was obvious, the woman didn't understand, and still kept trying to reach her. What was okay when she was lying in a familiar spot, under the protection of a table was NOT okay out on the street, with nowhere to hide!
So, it's likely going to be one step forward, two steps back. You will need patience, patience and MORE patience.
Since I had purchased this dog to train as a hearing ear service dog, and possibly for showing and breeding as well, I decided to rehome her to a single lady who wouldn't put any demands on her other than being a pet.
It was a big disappointment, but I know it was the right thing to do.