My concern would have been 11. ... O-O 12. g4, and if I play h6 he's got a chance of opening up my h file. Am I getting all worried over nothing?
Najdorf, question about move 11
After 11... 0-0 12 g4 don't play h6 but play 12... Nb6 instead, freeing d7 for the N/f6 and preparing your q-side play at the same time.....
Do you think castling kingside would have been safe, given the possibility of O-O-O and a kingside pawn assault from White?
I've played the Najdorf as my primary weapon against 1. e4 since I started playing chess. The point you raise is valid and it's a scary prospect to face but then again, play something calmer, if you don't have the minerals for the Najdorf. Normally, White attacks on the King-side, Black seeks counterplay along the c-file and pushes his Queen-side pawns. It's a race.
My thought, for what little it's worth, is that white screws up with 7. Nb3 when black did not play 6. e5. Otherwise it seems to me that 10. ... 0-0 is the right play, as the knight might be better placed on c6 in some lines.
All of which should be qualified by noting I suck at actually using what I understand about this game in any practical way.
It seems that your opponent (White) was trying by changing the move order to transpose you into a variation of the Keres Attack, English Attack or the Perenyi Attack where Black's position is known to be inferior. 7.Nb3 is not an optimal move in this opening but does not automatically give White a losing position. It does, however commit White to certain plans of attack mentioned above.
I play exactly the same opening, so I can give some of my thoughts. In this particular game, white is probably slow due to loss of a move by bishop movement twice. But, nonetheless, idea is similar.
The general plan for white is to castle queenside, play g4 and h4 and so on. Black's plan will be to play in the centre with d5 sometime and place queen on c7 and rook on c8 and create pressue on the c2 pawn.
So, I have an improvement on the move 10. When white played f3, instead of Nbd7, I would prefer Nc6. How does that look to you?
The advantages:
1. Has the flexibility to come to c4 through e5.
2. If white's dark square bishop moves, the e5 followed by Nd4 is very unpleasant for white.
3. You can go a5 and b4 and trading with white's a3 pawn (possibly) and occupy the b4 square with the Knight to create pressure on the c2 square (which is the main plan).
In any sicilian, not just this one, my experience shows that Nc6 is a much more flexible move. I don't see the point with Nbd7 so much. It just blocks the other knight's movement when g5 comes from white. So, the d7 square must be vacant for the knight on f6.
Hope I made my point.
Here are the first 10 moves, plus White's 11th, of a game I played recently. I played Black. My 11th move was b4, which I have subsequently decided wasn't the best choice; nevertheless I won by resignation a few moves later. Chess.com's computer analysis suggested that I should have played 11. ... O-O instead, followed by Qc7. Do you think castling kingside would have been safe, given the possibility of O-O-O and a kingside pawn assault from White?