Mia went through some really nervous phases when she was younger. It was just recently in the past year or so that she's come into her own. Honestly what I did was to ignore her issues for the most part, tell people not to pet her (Which is easy for me because I can just shove Summer at them and Summer is more than happy to pick up the slack and get all the pets), and just take her to lots of classes. Mia really has always done great in classes and she knows that she doesn't have to interact with other dogs and people there but she's learned to be okay with them around. I also find training just plain strengthens the bond between the handler and dog. The more Mia trusts me, the more she seems okay with other people.
Honestly, just doing that and now I have a dog that goes up to people on her own and licks them. I honestly never expected that from Mia, but as she's gained confidence, she's really become a lot more social. My trainer does not believe that Mia used to be shy at all, lol.
Anyways, I would just try more hands off approach.
Mia and Summer