It was a good game, I just my position by the end. Where did I go wrong?:

you probably want advice from someone rated higher but i would say you lost because you failed to capitalize on your material advantage by developing your queenside knight, moves 11 and 24 you had the tempos there to bring him out why not ask him to report for duty?

Your mistake was to continue to attack without fully developing your pieces@ move 18 was you first mistake NG5, should have played N(b1)D2 completing your development after that you should be able to capitalize on your material advantage easily; for instance 18...DH5; 19) KF1; QH1+, 20) NG1, RG6; 21) RXN, QXP+; 22) KE2 and blacks attack runs out of steam.

Your mistake was allowing your opponent to have too much counterplay.

In fact you have been playing with 2 officers less than your opponent. From move 15 he had all his material involved in the game, while your knight and rook on the queenside still are standing still in the garage. Of course you loose with a rook and a knight under.

All your material is in your left corner with your King in right corner before the end of the game. You giveth to your oponnent to much time and space and position of your King was weaker and weaker. Maybe weaker opponent couldnt you it against you, but this one is rather crafty and very good...

This game is a very good lesson how to sacrifice your material to win!

I agree with mauriciolopezsr, you started tactical moves against the bishop with half of your forces either on the extreme left or right.

 The tactics just weren't there.  

19 Qd3 was better than Qb3 (you want to protect your king side), and then developping your knight and your opponent has nothing to show.

20 d5 ? you should have developped your knight 

Unfortunately black got some tactics.  In the future when you're a clear piece up it's easiet to finish up development.

Just clicking though it quickly I think your moves were reasonable enough.  The moment I start to question you was with 21.d5.  The tactic on the bishop has failed, to time re-focus on development with Nd2.

I'm sure serious analysis would find better, but a very practical continuation, and what I probably would have done, is capture twice on e6 on move 14 followed by Qb3 to force a trade of queens.  A piece down in a simplified position, black has nothing to hope for.

I think maybe 19.Rxc6 would solve most of your problems with the mis placed queen.  

thats not even possible :)

Try Rxe6 instead.

The general theme of your mistake was not developing. Simply Nd2 at some point would have won you the game.

Sorry, e6.  But the tactic wins because it then lets you get your undeveloped pieces working.

Quite an interesting and well played game.

One inaccuracy was the maneuver 14.De2 and 15.Dc4 wasting a tempo. 14.Qb3 would have been better.

A mistake was 21.d5 ? breaking the pin of the knight. Instead of that it was high time to develop the queenside with Nd2 and get these two missing pieces into the game and to control your back rank.

24.Kh2 ? is understandable but brings the white king into mortal danger. Now you are punished for the not completed development.

So the major mistake was not to develop the knight on b1 and the rook on a1.

Remember that all your pieces have to join in the game.

In all the Chess.com videos I've watched on openings, they all stress that the opening is not complete till your rooks see each other.  But I'm not a master level player either.  

You seem like you're wasting tempo on some moves. Other moves you don't develop pieces enough opting instead for an attack e.g. 21. d5. I think Nd2 or Re5 would be better... IMO :)

I would have played 14.Qb3 instead of Qe2, just maximizing the pressure on the diagonal. 14...Nf8 becomes forced 15.Bxe6+ Rxe6 (If the Knight captures you can simply push the pawn on d4 since the Black Queen is pinned to the e1 Rook) And now, you are up a piece remember that he gave you one on h2. So you can just enjoy a winning position with 16.Nf3, with threats like Ng5, then you can develop the rest of your queen side pieces etc.

At the move 14. you had free piece (kNight). So simplyfing position was easiest way to victory, 14. Bxe6+ Rxe6 15. Rxe6 Qxe6 16. Qb3! with inevitable trade of Queens (better if he starts trade, and if he moves his King of the pin, it would be waste of tempo already). Then probably Kf1 would let you take your time in development (preventing Rook attacks on e file).

Then there you were gradually losing your advantage. And 24. Kh2 was very weak, after 24. Nd2 you would be still better.

A nice finale by Black (and 27... g5 was actually even quicker).