Establish that your dog is barking first., barking at the postman etc is fine, continuous barking is not. Great that you have asked your other neighbour and she has not heard barking.
You need to do your usual routine and then wait outside the house and see if you can hear any barking, doing this plus using the camera should enable you to see if the barking is a problem.
Ensure your dog is walked, has the radio on/curtains closed, and has a chew to occupied her.
The process for reporting a dog barking is to the local authority, who will investigate under the Environmental Protection Act, as a Statutory Noise Nuisance (which also included loud music etc).
They will probably ask your neighbours to fill out diary sheets with any times the dog barks, that way you can then refute any alleged barking that happened whilst you were at home and can attest the dog did not bark. The council may then do some onsite monitoring themselves, or install noise monitoring equipment.
They are looking at the times of barking (so antisocial early morning, late night), the duration and frequency (for a few minutes or for hours) and the volume (one dog or multiple dogs)
In all honesty, it is very hard to get one single dog barking classed as stat nuisance so legally you probably don't have a problem.