How to find a reason to continue during periods of no improvement

Glad to know I was able to help you in finding out the main problem. Now that we figured out what is causing the issue, you can look for ways to work on it.  

I leave it to helpful members like Chessguy140 to take care of the rest.

@njosnari. How are you training tactics? Calculation, visualisation and evaluation of the visualise position are core chess skills. IMO puzzles are a great way to develop them. My ability has strengthed considerably over the last 8 months by doing daily puzzles. There are two ways to do puzzles. Turn down the rating until the puzzles are easy enough for you to solve quickly (10s of seconds) and then grind. This is developing quick pattern recognition. The second method is to turn up the rating so the patterns are too hard for your quick pattern recognition. These may take minutes to solve and will require you to calculate and visualise different candidate moves. You should aim to get them correct first time so dont move a piece until you are confident you've found a solution. In practice you'll get some wrong. It's this second method that will help develop your calculation and visualisation skills. You need the puzzle rating to be hard enough that you have to work, but not so hard that you cant find the solution after 10 minutes. If you use the rated puzzle engine it will find your level and automatically increase the difficulty as you improve. Based on my experience, even with daily practice, expect a delay of several months before you feel the improvement coming into your games but then your brain is younger so it may come quicker.

I consider pattern recognition and visualisation to be different skills. Visualisation is the ability to think about the position in your mind before it appears on the board. Pattern recognition is immediately recognising an arrangement of pieces as a tactical pattern and may operate on the actual pieces on the board or on the visualised position. Always verify your pattern recognition by calculation and visualisation, pattern recognition is fast but not always correct. It is easy to miss defensive resource so verify before playing the moves.

Pattern recognition training is developing your intuition. Calculation and visualisation training gives you the skills to verify that intuition.

Quickest way to develop pattern recognition is to repetitively  watch the solutions of tactical puzzles until it sinks into memory. After seeing his games, I think he has moderate pattern recognition capacity to surpass his rating stage, but he lacks visualization. Like he knows that Queen and bishop battery is a danger towards his f7 square. So, he decided to play knight h6.. 

However, he failed to visualize the further threats. He didn’t calculate that the knight can be chopped off by the dark square bishop.  Removing his defender. (Note that I am completely saying this from my memory as I saw his game yesterday)

It’s quite clear that he has a hard time seeing the full board. It’s not like he doesn’t know that the dark square bishop capturing his knight will also hamper his castled king side. It's just that he couldn’t visualize that far in depth. He lacks depth in calculation.                      

Also, I have noticed that OP frequently  plays 5 minute games. I'd recommend playing 30 min matches or longer for improvement. Play less, but give 100 percent. In that way, you will have more wins than losses.     

I understand. For me, method 2 in my post above, solving harder puzzles with tactical depth of 3 to 6 moves (roughly), 5 a day every day, has helped a lot. Find a set of forcing candidates (cct), evaluate strongest replies etc. They key is to be committed to getting them correct first time and not guess moves. You will then make yourself calculate and visualise until the eureka moment.

I do disagree on watching solutions to train pattern recognition. It's a bit passive. Might not be what you meant. The brain needs output as well as input to learn. I think people should be solving the puzzle, so actually spotting the solution and making the move.

It worked for me. This idea was suggested to me by an IM.  

I have beaten a NM and a FM. That's my success so far.  

I haven't beaten anyone like that so maybe you're onto something.

Yeah so it sounds likely that you have some degree of aphantasia. You don't have to be able to conjure up detailed images of people or items in your head to not suffer from the condition. Oftentimes when I imagine things they come out kinda cartoonish unless I make an effort to add detail. So if I visualize a banana, I visualize a cartoon banana, and I only add more graphic/detailed/realistic aspects to it if I need to. But I can still visualize a realistic image of a banana or an apple. It just takes more of a conscious effort.

Blindfold chess is very difficult for everyone who is below master level, so do not think as if people without aphantasia can do it fairly easily. But if you cannot easily imagine a cartoon apple or a drawing of a stick figure in your head, then you do have aphantasia. That is not the end of the world- wikipedia lists several highly successful people who have the condition- https://en.wikipedia.org/wiki/Aphantasia . But anyways, you do not need to have your eyes closed to visualize images, Even when the eyes are closed, I see the fluid darkness just as much as you do, but I also imagine the image of, say, a white bishop. The image does not replace the darkness whatsoever. Likewise, if my eyes are open, the image does not replace what my eyes are looking at, I can imagine images while still processing whatever visual stimuli is coming from the exterior world, if that makes any sense.

If you want to do something about this condition, you will want to see a psychologist or a neurologist for a formal diagnosis. They might be able to come up with some sort of experimental treatment for you, although it sounds like research on the condition by neurologists is in its infancy. At the very least, you would have a formal diagnosis from a professional.

As for chess, your condition will make things more difficult. You might want to seek out other chess players with the condition and ask them how they managed to get good. You might also look to see if there are any training methods specifically for people with aphantasia or who are blind. Regardless, I do not think you should play live chess anymore. You should stick entirely to daily chess. The analysis board will be a massive help for you and your calculations. Instead of doing the calculation entirely in your head, you can move the pieces around as you try different variations. The analysis board is a good tool for everyone, but it should be especially helpful for you and anyone with aphantasia.

I realize daily chess is a time commitment that you are not used to, but I recommend that you play games that allow for multiple days per move. I think the standard is 3 days per move. If that is too quick, you can increase to 7 days or 14 days. If that is too slow, you can decrease to 1 day. As long as you do not end up playing several games at once, daily chess should be manageable for any working adult with a smartphone. 

Personally, if I had aphantasia, I probably would not play chess very much, if at all. I would stick to playing something like Old School RuneScape. I assume you are familiar with that game, given the fact that "noob" is on your profile picture. Things like videogames or whatever do not rely nearly as much on visualization, calculation, or pattern recognition as chess does. But that is just what I would do. Clearly, there are people who are able to attain master level and beyond despite their disadvantage- https://www.quora.com//Would-an-aphantasic-person-ever-be-able-to-play-chess-well/answer/H%C3%A5kon-Hapnes-Strand/log . So it is up to you. Regardless, you should seek out a professional who can formally diagnose you with aphantasia if you really have it.