@StopBloodyBarking
I had a dog that was similar to yours. A different breed, can’t say what as hugely outing.
My dog was like yours, pretty much from the first week,
Took the dog to puppy school four times, socialised the dog, did everything right.
It never occurred to me to take the dog back as I thought that the dog would improve with time and training. No.
The dog had some medical issues that didn’t become evident until some 5 years later. Vet gave meds. Illness nothing to do with behaviour.
Like you, I was ground down. Very much so. I also was doing all the doggy care myself. Luckily the dog was very bonded with the members of the household.
Eventually, I went to the vet and explained the situation hadn’t really improved and it was unfortunately really getting me down as I felt I couldn’t go out and leave the dog at home alone.
The vet recommended a rescue that works with experienced foster carers, doesn’t ever PTS, and won’t rehome until the dog is ready.
I found out at the beginning of December that my lovely doggy (and the dog was lovely with me. It was everyone else that was a problem) was successfully rehomed after only 3 months of retraining and the rehoming has been a success.
Maybe being professional, experienced dog trainers was different, maybe the home life dynamic, who knows? The rescue person said that the foster carer could tell that the dog had been well loved and well cared for as apparently the “framework” became evident from the start - my dog would sit, stand, down, in, out, etc., etc., but just became more and more reactive with each passing week.
Please don’t PTS until you’ve looked in to a rescue specific group.
But please don’t ask your current vet for any advice.