The double hane at move 15 seems too aggressive. It creates weaknesses for you which he can exploit - which he did by playing at 'a':
$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . B O . . . . . . . |
$$ . . . . . . a X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . B O . . . . . . . |
$$ . . . . . . a X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |[/go]
Instead, you can still make him very uncomfortable while keeping your stones strong by playing at L17:
$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . O . . . . . . . |
$$ . . . . . . B X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . O . . . . . . . |
$$ . . . . . . B X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |[/go]
His options are not pleasant. He can run along the second line:
$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . 3 1 O . . . . . . . |
$$ . . . . 4 2 B X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . 3 1 O . . . . . . . |
$$ . . . . 4 2 B X O O . . . . . |
$$ . . . . . , . . X X . X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |[/go]
...in which he gets one point per move while you get a wall that is worth something like 3 points per move.
Or, he can try to fight:
$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . 6 O 5 . 4 . . . . |
$$ . . . . . . B X O O 2 . . . . |
$$ . . . . . , . . X X 1 X X . . |
$$ . . . . . . . . . . 3 . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . 6 O 5 . 4 . . . . |
$$ . . . . . . B X O O 2 . . . . |
$$ . . . . . , . . X X 1 X X . . |
$$ . . . . . . . . . . 3 . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |[/go]
...which probably ends in his death.
Or he can go for territory:
$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . O . . . . 3 4 . |
$$ . . . . . . B X O O 1 . . . . |
$$ . . . . . , . . X X 2 X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |
- Click Here To Show Diagram Code
[go]$$Wc
$$---------------
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . O . . . . 3 4 . |
$$ . . . . . . B X O O 1 . . . . |
$$ . . . . . , . . X X 2 X X . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . O . . |
$$ . . . . . . . . . . . . . . . |
$$ . . . . . . . . . . . . . . . |[/go]
...which forces you to make your wall very strong, and and lives in gote while you prepare to attack on the right side.
Note that you do not have to be ultra aggressive. Often the most dangerous move you can make is a solid move that expands and consolidates your power, because if you then start a fight, he will lose it.