I'm going to say this one last time because I really do feel sorry for you.
You think you're not playing in a vacuum but you are. All this well intended advice here is getting you nowhere. You say that you play league matches and you practice at home. That formula isn't working for you. What's missing --- and this comes from experience --- is becoming a regular in your local pool room, hanging around watching players and playing other people every day, not just league nights. When you play other people on a daily basis and become part of the sub-culture of a pool room, your focus changes from internal to external. You need to get out of your own head. Be around other players. Watch them. Listen to them. Become a regular. Practice with them. Match up, even if just for the tab.
Continue to play your leagues, and spend more time in the pool room and less at home alone.
You don't believe that something like that would help your fundamentals improve without your practicing them, right? You'd be surprised.
Couldn't have said it better. Particularly the last paragraph. I tried saying something similar back in post 11 but don't think I was forceful enough. You were.
How many have you seen doing this over the years? Right now I know of 4 guys that come in the poolroom who are members of this club.
What is going to happen to them over the next few years is very predictable, see post 18.
This phenomenon started with the internet. Back in the day if you wanted to learn pool it had to be at the poolroom. It's still the best way although the internet is a great help if used properly.
Only thing I disagree with in your post is "continue to play your leagues" I'd amend that to continue to play the 14.1 league.
IMO there are zero reasons to be in the APA other than to have a night out drinking with friends. Doug can correct me if needed but I don't think that's his objective.
I heard him when he said at 67 he wasn't looking to be a world beater just a good hobbyist. On the other hand he seems serious about improving. In that case it would seem prudent to get the most bang for your buck. JMO but that's best achieved taking Fran's path.