Did you have this puppy checked for a microchip? I saw that it was suggested but didn't see where you posted you had her scanned.
If this girl has not been through service dog certification how did you get a doctor to get you a prescription for her
You might want to try Facebook...I know of dogs that have been reunited with their owners from posting on a lost/found dog page there.
Good luck in finding her owners. If they are like any of us, I'm sure they are devastated.