Me, that is, not Mouse 
Long story, sorry....
He's always been a tad nervous, but settled really well (he was six months when we got him). These past few months, we've had occasional barking or growling at visitors, and once or twice growling and/or air snapping at the kids. Seemed to get a little worse with time, in spite of all the training, all the love, all the carefully researched advice.
dh (who is most bonded with Mouse, as walks him most) thought I was being neurotic, worrying about him 
Then when we were on holiday, the dog-sitter (who loves him) reported growling at children who petted him nicely at the pet shop, and at her adolescent son when he visited (lives with his Dad). We took advice from the rescue, who said he hadn't been socialised early on, and to go back to basics - get kids to ignore dog except to feed him his meals, give treats, hold the lead on walks: ie positive things all the time.
Two weeks of no problems, and all visiting kids asked to help feed Mouse, but ignore him otherwise.....then Mouse jumped up at/snapped/barked at the vet's nurse, who runs their puppy training classes. Then he growled at another vet nurse. She was shocked, but helpful, and said he was a lovely boy and deserved to be helped asap - so made appointment with vet, who has referred us to some very experienced, accredited behaviourist who should be in touch next week. Apparently they have a lot of success with fear aggression (which it probably is - he only reacts when petted too long/by strangers) so I suppose I should hope it'll be ok.
Problem is, I feel a bit hopeless...and anxious..for Mouse, and for us, and also guilty. I feel I've let him down, let our family down for choosing an unsocialised pup (I swore I'd only take a dog fostered with kids...and he wasn't).
Any happy stories about behaviourists helping turn this kind of problem around? He really is a lovely boy in so, so many ways - great with dogs, obedient, full of beans. I'm worried sick it won't work 