Why do I convert like a Baboon? help me

I am just in shock with how bad I play in winning positions.

I know I should try to deny my opponent's counter play but instead I just believe their ideas are more dangerous than they really are and just almost mate myself for no reason, or at the very least make their non working ideas work.

This was 15+10, so I had plenty of time... I'm happy it turned out OK but I've really had enough of this horrible quality of middle game. 

I'm posting this because I feel I have a real problem to see correct moves and to see in advance the opponents threats when I "feel" safe, or when I have multiple options, I seem to always consider some of the most direct and strong ideas but disregard them for some stupid reason.

I want to fix this. This is unacceptable. lol

I wouldnt say even from my perspective that it was that bad of a conversion i think you were just looking for threats and probably trying not to get tunnel visioned on trading 

Maybe conversion is the wrong word
But I feel sometimes the opening or early middle game play from my opponents is just 4 question marks blunder and I always allow counter play .
My question is how do you work on this aspect of the game?
Puzzles train your general calculation , patterns, and to find singular ideas that win when the opponent does have strong threats if you misplay.. but in winning positions with multiple options, how do you train playing actively while at the same time allowing 0 counter play?  Finding ideas that are pressing with the attack but at the same time concede 0 risk? 

Because obviously if you just try to hold everything and focus only on denying counter play while up a piece that normally is what somehow invites counter play, you becoming passive.

Probably just practice. The saying goes the hardest game to win is a won game. 
(or something like that) Unless you have a completely dominant position not allow counterplay is impossible

That wasnt even that bad but if you want to practice then just play more or try to think how could i get in an endgame/ open the position. Its easy to lose up material in a closed position. Almost impossible to lose up material in an open position if you think logically

A cornered animal is the most dangerous

No one can help you. 

Just learn to convert better. The problem is when you're winning, you think the game changes, you can relax, or play however you want and will win, thats not how it works. Yes you're "Converting" but converting still means pushing your advantage, no matter how big it is, to a win. You haven't won yet, you're just ahead.

And if you're ahead, you can fall behind, if you're not careful, or even worse, become one of those idiots that cries about the stalemate rule because theyre too garbage at the game to convert a 20+ point material advantage to a checkmate.

Is there something wrong with 20.Ng6 ?

That's actually a super instructive thing to point out!

No idea how but I even missed that when analyzing and it's quite obvious. In the game I was afraid of c4?? which is a blunder, so I disregarded my natural move Be6, so Qe7 was basically without much thought, after calculating Be6 and deciding it's risky.

But very instructive:

1. Never play moves quickly after calculating a different move and being frustrated that it dosen't work.

2. It's better to control a knight on the rim than to attack it.

3. If you attack a knight, always look for forks, even if you think the knight is dead or weak or misplaced so you assume it's not threatening.

Stockfish dosen't think 20.Ng6 fork is amazing because simplifying helps Black and there is Qg5 giving up the rook but activating the queen nicely... But still... That was not the idea of Qe7?!.. I do think this touches on the subject of the post though that I really struggle to see any opponents threats when I feel I'm winning... And I want to fix this / find a way to work on this aspect

Yeah, it may turn out to not be the best move, but you gotta at least see it. It also might give white the best practical chance in a timed game between humans. At Qe7, my first reaction was "ngyaaahhh!!".