I've just noticed - 12. Nxd8+ should have been Re1 and not the other way around. Then I threaten mate with Re8 right?

Hey,

I don't think that moving Re1 before Nxd8+ will do you any good. He will sacrifice his queen for your rook, but you have to take his queen with your bishop and so his rook loses the threat. After you take his queen, he will take your knight with his bishop, you will take his knight with your bishop, his king will take your bishop and you will take his knight with your pawn. You end up with 1 rook less than him and with not that great of a position.

The only thing I could come up with after Rxg7+ is movng your knight to b3 to stop his queen from going to the quickest escape and also advancing your knight to possibly threaten his knight when you move your knight to c5 and that would leave the bishop to do his mate (this doesnt really work but possibly something along these lines).