plz see this game and tell me what was my main mistake? i played as black
20. g6 would have been better (harasses the queen and stops the potential mate at h7). Followed by Bf6-e5 maintains a good post for the kB.
Overall, your 2 bishops (considered an advantage) never got into the game
In the opening, as you have opted for the English attack, 6.Be2?! was an inaccuracy maybe even a mistake 6.Bc4 was the correct move. Apart from that your opening is fine, I'll look it all over later in more detail. Hope this helps a bit :)