So sorry to hear your cat is lost. It might also be a good idea to contact the RSPCA as I think they have a lost pets register.
I previously lived in the Thorburn Sq area and there are a lot of friendly people and animal lovers living near there. And I always pay close attention to lost pet notices on the neighbourhood trees and shops.
I'll keep an eye out if in the area. Do let us know if you put any pictures up online or better yet if you find your cat.