My luckiest win (against 2300+ classical)

I can't believe it... I am not an opening expert on the Scotch (I just know a few basic moves), but apparently got my opponent into trouble where he can't castle. According to Stockfish analysis, even though he can't castle he is apparently still fine, but in middle game he makes some blunders and also time trouble.
To his credit, he put up a good defence, I didn't checkmate him or anything.

My favorite move was 22... Nxd4. I calculated that the knight can't be taken, even though there were 3 pieces (Q, R, N) that were targeting it.

Please help to analyze and tell me what went wrong or can be improved (for both sides). How could I have improved my attack, and how could my opponent have improved his defence.

Also, was my 6... Qf6 a bad move or still ok?

Thanks!

* Btw in case you are checking out his rating, he was 2300+ before he played me.

5.Nb3, 6.Nc3 already looks dubious to me. Black indeed gets a powerful bishop on b6 targeting on f2.

The main line goes 5.Be3 Df6 6.c3 etc. (I'm not a Scotch expert as well). After move 7, White already has weaknesses in his position and a king still in the center.

14.Nxe7?! (I would have played 14.Qf3 followed by Be3, with an excellent position). There is no need in exchanging this powerful knight on d5.

Your 6...Qf6 is OK, but 6...Nf6 were more natural development.
His 7 f4 weakens his king, better 7 Qe2.
Instead of 9 a5 he should have developed 9 Bc4.
You played very well, he made more mistakes. If you had shown the game without the ratings of the players, I would have thought these were the other way around. Well played.

For the future I recommend 5. ... Bb4+ 6.Bd2 (6.c3 Be7) a5. Black pretty much equalises already and you don't have to know much theory.

As much as you need to know:

1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4 Bc5 5.Nb3 Bb4+ 6.Bd2 a5 7.a3 Be7 8.Nc3 a4 9.Nc1 Nf6

@Tethys
Your criticism of 5.Nb3 is misplaced. It's a playable move which has been employed by the likes of Anish Giri. You can even find a video series about this line on chess24, recorded by his wife.
I have to admit, though, that it is not my favourite move either.

Nobody knows anything for sure about openings.
4...Bc5 or 4...Nf6, 5 Nb3, or 5 Be3, or 5 Nxc6, 5...Bb6, or 5...Bb4+, or 5...Be7 it is all a matter of taste, style, and fashion.

7. f4 feels wrong.