Old Chess Dog, thank you. I am sure it is something to do with the way older people think and I am interested in this process. I watch my own son and other kids, 6, 7, 8.. yrs old and I am amazed by how quickly and well they learn. knowing that Magnus Carlsen at 13 was a grandmaster (and seeing these games online) shows how well young minds adapt. I am interested in how this method of thinking works and whether there are ways adults can learn in such a way so I'll check out your videos.
Batman thank you for your analysis. You'll see that I did identify 18.Nd5 as my biggest mistake. I gues what I should do is look at alternatives and FOLLOW THEM THROUGH with calculation to see what might have been better. Casper is right though, sometimes it does take an outside eye - a skilled one - to see where problems are. It is difficult analysing positions when my positional understanding isn't developed.
I think Till's offer is amazing and you should accept it with both hands. Just see what he has to offer. The problem with analysing your own games by yourself is the same problem that occurs when programmers debug their own code. It reminds me of the quote by the famous programmer Brian Kernighan: "Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it."
Properly analysing a chess match is tough, since it requires a fairly deep knowledge of positional play, strategy, tactics, principles of attack etc. IMHO without outside help, analysing your matches is a waste of time. Apart from the obvious blunders that you can most likely spot yourself, you will only sporadically come up with new insights that are solid enough to be applied in every match. And it is exactly that which makes you a stronger player. If you were able to improve in a self-contained way, you would somehow access latent chess knowledge you already had in you, all by yourself, which I think is very difficult, also given the plateau you can't seem to get off of.
I notice it in my play as well. Sometimes positions come up that I can't analyse myself due to lack of chess knowledge. Turning to outside help, e.g. instructional videos here on chess.com or asking an instructor, suddenly make it clear what I had to do. I wouldn't have come up with those structural improvements all by myself.
To make a (way too) long story short: grab every opportunity for free lessons. Grab a hold of the basics (as mentioned above) and expand your knowledge with the help of (much) stronger players that you feel comfortable with instructing you. Find your favorite teacher and see if he has posted free lectures on Youtube. Good luck!