How did you manage to lose this game

You had a solid opening and played well in the early middle game to take the lead. In fact, you outplayed W through most of the game, until around move 93 where you got lost in the fighting. If you had sidestepped that fight (giving up two stones to cash in on the K17 cut), I think you would have won.
The move I would criticize most is

. It looks like you are trying too hard around here to gain a little extra efficiency, but this move leaves bad aji. It would be much better to play the very solid good-shape "honte" move M7. After that, the B center group would be secure forever, leaving B free to play strongly elsewhere. As a bonus, W would still have to worry about his thin shape around here.