Game for analysis - where are the holes?

Thanks for any insights. I didn't review the game with an engine yet, as per the posting guidelines. I've already noticed a couple of things that went super wrong, but I'm still a bit blank regarding what I could have done better (before losing my cool and the tactical game of course).

Edit: Also, did I do anything wrong regarding how to post the game? I have noticed it shows on the computer but it only shows the moves until 1st comment when reading the forums through the Android app.

12. ... ne8 is a terrible move that qualifies as a positional blunder.  It undevelops the knight, and gives it exactly nowhere to go except back where it came from.  From e8 it controls no squares, and just gets in the way.  Stockfish confirms that your turned a small edge into a sizeable deficit with this one move.  A positional blunder and something you can learn from I think.  Nd4 is already playable by you now, but white's nd5 looks very annoying so I'd probably play e6, restraining his knights, aiming to play d5 in the future, likely after playing nd4 next.  

22. ...bxg2 misses a devastating attack, rf4.  Wouldn't blame yourself for missing it per se given your rating, but at the same time if you had noticed that the white king's position was airy and looked at whether that could be exploited you likely would have spotted it.  After, all, the tactic is actually very simple.

23. ... qc6+ looks logical, allowing you to keep the pawn pxp.

24 not sure why you lost your cool, you are down a pawn but white's king and pawns are weak.  Position is roughly equal.  

Thanks ArtNJ! That's great stuff.

Thanks. I'll be sure to study this position more. You're right that this one move changed from a black to a white advantage on the position.

I'm still struggling with the knights here, that's certain. You say I can play Nd4 right away but after Bxd4 cxd4 I'd lose the c4 outpost. Maybe the c4 is a good advanced pawn supported by the dark bishop? But the dark bishop is not even supporting the pawn, because of the f6 knight. After 14. Nce2, defending the knight and attacking the pawn, stockfish gives it a -0.60 score but I sure don't quite know why or how to increase the pressure. It shows 14... e5 as a continuation but then I have long-term blocked the dark bishop. Maybe it could later go to h6, since my opponent doesn't have the counterpart?

With the computer analysis now I see that 19...f5 was actually a good move (I had thought it had been bad), and that 20... fxe4 would give me a big advantage already. I sure didn't see it, though I knew Kg7 was meh at best. Oddly enough, most other "waiting moves" still kept me a clean pawn ahead in score.

After 20... fxe4, stockfish takes with the rook for white and I can't see why either. I only really looked into him taking with bishop or knight. Apparently both are bad with 21... d5 and 21... Rf4 (respectively) already. I must confess I can't quite grasp why either are so powerful here, I'll have to study these positions more. They all give black a big advantage that I don't see myself.

About 22... Rf4, you're right, it's devastating.

I think I didn't spot it because the e6 pawn looked so dangerous to me. After e7 Rde8, Ne5 the knight is permanently there causing havoc and protecting the e pawn, my rook is passive, and in general I didn't like what I saw. So I think I was 100% focused on getting rid of the threat and didn't quite consider I'd have time to create as strong a threat of my own.

Not sure either. Probably something I need to look into in my thought process. 

Also stockfish suggests 24...Bxc3 as a continuation here. I'm not entirely sure why and during the game I wouldn't have seriously considered trading my bishop for a knight towards this endgame. Though now having a look at it after Ne5 it'd look like good knight vs. bad bishop. 

Thank you very much for your help, it was invaluable!