space advantage

@1
"how I could have improved my game or mistakes"
22 Nh2? makes no sense. What is the knight doing there. Centralise it 22 Nd4.
20 Bf4? the right idea to exploit Re1 - Ke8, but the wrong move 20 Nxe5
11 g4? Much stronger 11 Bf4 striking at the backward pawn d6
10 h3? Loss of time. Better 10 Nb5 striking at the backward pawn d6.
9 O-O-O? Better 9 Nb5 striking at the backward pawn d6.
"how do I use my space advantage" ++ Space is overrated. You cannot win on space alone.
"the opening was rare with h6" ++ The late IM Basman used to play that.