Critical moment from a recent game

Ok, I just wound up badly losing this game, and I was looking to work out where I went wrong, and why I made the mistakes I did!

Look at this position:

I have just played 11.g2-g4 and it seems like I am in good shape, with fast play on the kingside to counter Black's queenside action. My opponent now makes a move in the centre with 11...e5. Surely a critical move to meet.

However, I didn't see a great way to meet it at all. I had a look at 12.f5, but then 12...d5 looks quite good for Black. 12.g5 is met by Ng4. In fact, this is the really annoying thing, my g4 square looks like it is getting undermined. I think I made a bad mistake with 12.Rg1, and after 12...h5 it didn't look good for me. Maybe 12.h3 was a better idea, with 12...h5 13.g5 maybe ok? Anyway, I'd like to know what's important in this position, and of course, what the correct course of action was (or if I'm already screwed). I'm inclined towards h3 at the moment.

Bump.

I was looking at the surprising f4xe5 which semi-opens the f file for your queen to x-ray black's weak f7 square and perhaps some coordination by getting the bishop to c4 (to take advantage of the newly opened diagonal to put additional pressure on black's weak f7 square) and then rook to f1 to form a battery with your queen and rook for even more pressure against the f7 square. And g5 to remove the defender (knight) and uncork total devastation on black's kingside. 

normally, why would you undertake kingside action when the opponent hasn't castled. you are only weakening your own king. it is advisable to play in the center in the beginning and then undertake a flank attack only after the center is resolved.

one thing chess mentor told me is that flank attacks work best when the center is closed/blocked. because

1) the opponent is unable to shift forces to defense because of the blocked center.

2) the opponent cannot counter in the center.

in your game this principle is highlighted as your flank attack is undermined by the opponent grabbing squares in the center which you have abandoned to its fate.