In your comments you say that 14... h5 is the only way to prolong the opening, however I see it as a bad move since he loses that pawn at least. Your opponent would have been better off playing something like 14... b5, IMO.
15... g6?? As you say this leads to forced mate, so obviously your blunder was not playing the mate.
16... b5 At this point you appear to believe that this is a futile attempt at an attack, yet with correct play this would have yielded quite well. You don't have a major advantage here.
18... Na6?? Your opponent loses a knight with this move. Assuming of course he doesnt let you mate him, which he does.
19. h5! [The king will be mated shortly.] Not correct, I'm afraid. If your opponent had just played something natural like 19... d5 he would have been safe (although as I said, probably a knight down due to Na6).
Nice mate, anyway. 
Analysis desired and suggestions please. This was a 3 min blitz game so we did not have that much time and I missed a forced mate
. It's basically a game with opposite castling and trying to rip open the other guy's castled king. I think that passive playing led to my opponent's demise.