If he seems happy in himself, he will be fine. Our 14 year old terrier has been blind since age 4, and is now deaf and has dementia. But she is still content - hardly moves, and hasn't been able to go on walks for several years now - but potters in and out and we work round her. If she seemed unhappy, I'd know. Dogs do adjust - and if they don't, you'd know about it.
My dog went blind with a congenital problem that her breed is prone to. She took months to fully adapt but she did it. Years later I took her into a pet shop and the woman working in there went mad for her - turns out she had had the same breed dog, but her's had to be PTS at a very early age as it also got the eye problem but, she said, it could never adapt to being blind - was very obviously scared and distraught all the time and in the end the vet advised her to have him PTS. Same breed of dog, same problem, equally caring owners but different outcome as my dog (slowly) adapted - her's didn't. So I think your dog is fine - you would, like this lady, know if he wasn't.
When my dog went deaf she was fine with it. My neighbour also has a deaf dog and she is also perfectly fine.