May I ask for advice?

Hi guys. I'm lost in thoughts in step 19 after analyzing. The game analysis told me moving the pawn instead of taking rook after the fork is a good step. But I can't seem to find a reason why it is so. Aside from the blunder of moving knight, is there other suggested tactics I could better apply in counter this situation as the queen and knight push pressure towards my king? Any help would be appreciated. Many thanks.

The key to the whole game is this position:

You are doing well here, but you allow Bg4 and that pin is really annoying and you lose all your advantage. h3 or Nxd4 was necessary to stop the pin and prevent the damage to the pawn shelter around your king.

On move 18 f4 is recommended to allow the queen to cover some squares for defence. If you can play Qf3 you might survive the attack from his queen and knight and you could always take one of the forked rooks later. 

@Strangemover Thank for the advice, it was informative.

You are welcome mate, all the best as you try to improve 👍

Hi! My name is Lauren Goodkind and I’m a chess coach and chess YouTuber based in California: 

https://www.youtube.com/channel/UCP5SPSG_sWSYPjqJYMNwL_Q

Moving the knight to g3 is a mistake, since the f2 pawn is pinned.  Perhaps Qc2 would be better since the queen would be protecting the vulnerable f2 pawn. 

I hope that this helps. 

8 Re1? is a missed win. With 8 h3 you stay a pawn up.
9 h3? is too late, weakening and losing. You could just take 9 Rxe5 and the game is still equal.