3. e3 is worse than 3 Qc2 or 3 f3 in my opinion. One puts the question early to your Bishop in a way and the other prepares the center destroying e4. I don't play the White side of the Nimzo ever, it's more of an observation of better players than I.
6. ... d6 seems like it wants to be ... c5. You make a needless preparation that costs you a tempo later. Also, you want them to take c5 as it trades a good center pawn for a lesser wing pawn. Furthermore, it creates more tension throughought the game, keeping pressure on an otherwise un-pressured opponent.
12 ... d5 should be d5! from d7 but that was mentioned above. Good idea for creating a positive imbalance and then exploiting it.
15 ... Re8 is weak. Too passive, better is developing the Knight or Queen. There is no reason that the e file would open up. Don't follow guidelines mindlessly. Why do you put Rooks on half files? Because they might open. Is this one going to open? Not any time soon if your Knights vs Bishop plays out well.
19. ... Ne4 is bad for the reasons you suggest. One move drives it away and loses you a tempo. Also, doubling rooks is usually best done on the 7th and 8th files. If they have two bishops, don't give them free x-rays on your heavy pieces!
22 ... fxe4 would be absolutely correct if you had left your rook on the f-file like it naturally should have been. Thus far moving your rooks have only gotten you x-ray'd and lost your great knight to a shitty bishop.
At 26 ... Nf3+ you have won the game. Your knight cannot be dislodged except by winning the exchange. You literally can't lose if you don't move your knight...
Excellent play other than the game losing mistake. There were a few spots I didn't mention where you could play more prophylactically. In positions where you are dominant, constantly see what your opponent needs to do and prevent that. You could have locked up the Queenside totally as soon as you saw his bishop head that way.
Great work.
Here is a recent game of mine. I've only played in one tournament, and I didn't fare so well against even the unrated players, so I consider myself to be a moderately solid lower-echelon player, so you know where I stand. Besides the major blunder on move 30, this is about as strong a game I've ever played, so any feedback would be most welcome. Where do I have the right idea, where am I going wrong, etc.? Also, this is one of my first successful attempts at really closing down a position, so any thoughts there would be welcomed. Thanks in advance for your thoughts and time.