@ FirebrandX, Is 7 ...Qb6 better ?
And you are right about 13 .... Qxe5 instead of Qb6, as my engine suggests that 13 Qg4 is not a good idea as after Qg4 Qxe5 black gains an advantage of +1.51, while with Qb6 black ends up with -4.10 after 14 Rd6, which is a huge and decisive difference.
Start looking openings up in the Game Explorer. You can compare what you played with what masters have played in identical positions and what lines are popular and which ones aren't. This one is B96: Sicilian Defense: Najdorf Variation, Polugayevsky Variation
it's extremely tactical and complicated (as you may have noticed) and probably not the best opening to work on - yet. The great hypermodern GM Richard Reti in his classic "Masters of the Chessboard" recommends beginners play Double KP Openings whenever possible - as both White and Black.
http://www.chess.com/blog/NimzoRoy/endgame-faqs?_domain=old_blog_host&_parent=old_frontend_blog_view
http://www.chess.com/blog/NimzoRoy/chess-opening-principles?_domain=old_blog_host&_parent=old_frontend_blog_view
http://www.chess.com/blog/NimzoRoy/beginner-chess-book-recommendations
Is 13 Qg4 a good move ? Can't it be easily nullified by Qxe5
And you are right about 13 .... Qxe5 instead of Qb6, as my engine suggests that 13 Qg4 is not a good idea as after Qg4 Qxe5 black gains an advantage of +1.51, while with Qb6 black ends up with -4.10 after 14 Rd6, which is a huge and decisive difference.
I'm not one for engines just to say (nothing wrong with them but I'm not at a point where I can benefit as a player using them)... but I'm assuming that this is because black would have destoryed white's central pawn which was the backbone of whites attack. Black had to work it's development around the pawn since it controlled 2 useful squares. (This is beyond tactical play. This is just fundamental.)
This can serve as a lesson as to why dominating the center can give you so many options. You can choose which side to innitiate an attack on.
Can you point out the flaws in black's game