I'm Black. White about 1940

Let me review this one a little better later...

4...a6 is also not good because you have an advanced backward doubled pawn  ( In my personal style i typically have no problem getting doubled pawns but in this structure it is considered disadvantageous for black and white scores well.)

 7...bb7 is too slow in my opinion.  Its not clear at this point where u want that bishop.  I would also be more interesting in developing my kingside since i would want to castle that way and white is way ahead in development.  .  You may want to play your rook on the b file as well.  7...e5 seems best here making the queen move again, stopping any thoughts of e5 by white and grabbing more central squares

10...Qc7 was not best obviously, but your not losing the game.  Always watch for queen related pins.

14...f6 looks a little weird but at least he doesnt have a light squared bishop to take advantage of your light squares.  i just like developing the black knight to e7 immediatly.  white bishop not really doing much on g5

18...dxc5 is really when white starts having a clear plus. ...d5 was best.  f6 comes back to haunt u as well with the queen stopping your ability to castle and get your king out of the middle.

23. Rxe5+  is crushing for white.

white trades into about an even endgame after 24.  Bxd4? and qxc6?  a move such as ng5 is still crushing.  white is only very slightly better right before u drop the bishop in time pressure on move 30. Rybka gives 30...bb7 and white better by .13 which is miniscule.  i personally prefer black because you got a far advanced passed pawn, rook behind it, active rook on his 7th rank and a bishop on an open board.  he has the extra pawn but his pieces are not coordinated well.   he had a big plus in the middle game for awhile but squandered it away.  

A takeaway from this game is to find a better way to develop vs bb4 in sicilians which occur often.  I play bb4 type systems on white and one of the better approaches i find by black is to not allow the pawns to get stacked at all and have an nc6- ne7 structure.  check out some gm games

3...nd7 47%  3...nc6 53%  3. bd7 53%,  with big samples so nd7 may be best.