Help! I’m stuck

First of all, I have been playing chess for several years and I really enjoy the game.  However, I feel like it is kinda sad that my rating is so low since I spend so much time playing and learning.  I know all of the fundamentals and what you are supposed to do, I’ve read many many chess books and played thousands of games.  Bottom line, I have been about the same playing strength ever since I started .  I study games, do tactics trainer, analyze my own games but nothing...and I mean NOTHING helps me improve my play for the long term.  I can stare at the board for 5 minutes and still make a silly mistake.  I need suggestions as a last resort to improving my game.  Unfortunately, if I can’t make a noticeable improvement this year then it is farewell to chess.  I feel like that if I can’t learn from my mistakes then they are not worth making at all.  Please, I welcome all the help and suggestions on improving I can get.   I don’t want to accept that I am just innately terrible at this game

my only advice is to play a set number of longer games a day with the same opening and really focus on training tactics. quality>quantity

I mostly play correspondence.  A lot of my problems seem to come in the middle game where I have trouble developing any plans unless the opening is book moves.  It seems like half of the middle game positions I am in seem to have no direction and I have no idea where to attack and what my opponent is going to do.  I would say I am better in the endgame but I can’t get to an endgame too often because of my blunders.  Is it possible that I have just reached my max potential?  Because no matter how hard I try or look at the positions I am in, my opponents seem to outwit me in a way I did not see coming.

No, I think most people are capable of a lot more than they think. 1400 is likely not your max on the basis of you being willing to post and seek out advice. If you are having trouble in the middle game, my guess is that a short term problem is recognizing tactics both for you to defend and attack. Practice with the tactics trainer here, and play less games so that you are perfectly focused on that game. Good luck with your chess!

Check your messages. I sent you one.

I think I like positional play better than tactics.  I do well when I have a space advantage and I can squeeze the opponent until he runs out of air.  Can you recommend some openings or famous chess GMs to study that fit this kind of style?

Average move time is 4hrs 26mins - that's pretty fast for daily chess. Looked at your last loss - you played pretty well for a lot of moves then your opponent threatened your rook with his queen and you just ignored it and lost it. No tactic training or anything else can help you with that, it's just lack of concentration and making a move without looking at the board properly. Slow down, play less games, set the position up on a board in your house if possible, analyse variations, don't move until you have checked, checked and checked again. Remember how damn annoying it is to blunder and lose and force yourself to think carefully. 

That is a good point about the move time.  Considering the amount of games I have played lately, my average move time is pretty fast.  What gets me a lot is that I can’t seem to find any good attacking plans and I keep repositioning my pieces back and forth until I blunder. I feel like I would play a lot more accurately if I was able to consistently form viable plans.

Improving Your Chess - Resources for Beginners and Beyond...

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

Good Positional Chess, Planning & Strategy Books for Beginners and Beyond...

https://www.chess.com/blog/RussBell/introduction-to-positional-chess-planning-strategy