How to get my rating higher

 Just looking at this game. You blunder with 10... Na5 and the additional gift is the weak black field complex around f6. Whatever happened with 21.Rd1 (mouse blunder? hope chess?) you took the opportunity. 23... Qxf1 is another blunder. Do you find the better move? What are the names of the two basic tactics you didn't remark?

If you work in that way over your games and create a file collecting your mistakes in categories you will be able to do a better training. You should find out the motivs you're missing.

Your play is not that bad, that resigning to get better is the right attitude.

In my experience what holds adults back is the fact that strategy can be really intellectual, creative, interesting, etc. while tactics is extremely tedious. The best example of this is the popular youtuber who called himself backyard professor. As a total beginner he read a strategy book and thought he knew everything about chess. He started making instructional videos for chess... but he blundered pieces and pawns so he ended up talking a lot of gibberish. It's not an uncommon pitfall for adult players.

I assume you're better than BYP, but I also assume it's the same sort of thing holding you back. I recommend a book like this:

https://www.amazon.com/Back-Basics-Tactics-ChessCafe-Chess/dp/1888690348

And for every puzzle you can't solve off the page within 10-20 seconds, get out a piece of paper (and I like to set up the position on a physical board) and what you're going to do is write down your full answer using chess notation. Don't use it as an aid, only write down after you're done calculating. Include any variations.

What this does is helps you see your thought process. When you're wrong, play out your solution on the board and try to figure out why. If you can't figure out why your solution doesn't work, use a chess engine. For any tactic puzzle you fail it's very important to figure out why your intended solution doesn't work.

You'll discover most errors stem from not working hard enough at finding a good defense for the opponent.

Also for each puzzle you fail, mark the page number, problem number, etc, and try the puzzle again in about 3 days. If you fail it again, that's fine, it just stays in the fail list until you solve it correctly at least once.

Also try to understand why you missed the correct move. If you find a common problem it will help you improve... like maybe you often miss the opportunity for knight forks. Just an example.

I'd say completely stop playing games and do this a few hours a day, every day, for a month. This will help shock your system out of old and bad habits.

Then when you go back to playing games, make the time control really long. At least 30 minutes. If you can't find human opponents for this, then play against a computer.

During the game, whenever there is a tactical situation, you can even write down your calculations like you did with the puzzles. This makes it easier to see what you missed after the game. Even if you win the game, go back and check whether you were making reasonable calculations (they don't have to be all engine moves, but you don't want to have made any big errors).

Keep doing drills every day, and I'd say play less than 10 games a week. Do this for two months.

That's what I'd recommend to sort of break down your bad habits and rebuild some good ones. As I said in the beginning, it can be pretty tedious, but after you've done it, and made some good habits, you can go back to having fun and those habits will stick with you.

One thing to remember is, if you haven't improved in 25 years, you're going to have a lot of ingrained habits and ways of thinking... breaking them and learning new things is not going to be fun at first, but you can improve if you're willing to change.

     I looked at your games and I was very surprised. You are indeed very good and your low rating doesn't seem to correlate with your understanding.

    I think that 2 are the main problems. First, lack of focus and some silly mistakes that you could easily avoid in some key points. Second , despite that you calimed you have studied books I think your chess education is not so well-rounded. Maybe the problem is the various irregular openings you try to play.

    Obviously to improve you have to make something differently. You have to start working differently and try to see things from a different angle! 

      Here is my advice. First play longer games. That will help you maintian your focus for longer. Second , abandon all semi open or semi closed openings and play classical openings(1.e4 with white , 1...e5 and 1...d5 with Black). This initially will lead in bad results but it will probably have ,long term benefits. When something goes wrong in the opening , try to find out what that is and try not to repeat the same mistake. Ideally make an archive of mistakes and be sure you re-read them before you play.

      You don't need to play only long time control games. But play 2-3 every week and analyse them exhaustively. Make them your refference points.

     We can play a couple of training games if you want and I can show you how to use your own games to fix and improve your thinking process.