I do not see any glaring mistakes, just a few slack moves, which gradually let your opponent pull ahead. A few comments on the opening:
is too conservative. There is no reason not to pincer W tightly here, to apply maximum pressure. Both N17 and J17 would be good. I think I actually prefer J17, even though it appears to be an extension from the stronger side, because it makes a definite base for your large group. A simple continuation like J17-O17, P17-O16, Q14 would be fine for B.
is fine but not necessary. The right side is so open that B does not have a strong attack here, so a conservative pincer is fine, and the game sequence was good. It is hard to choose between R6 and R7 and R12 now, so B could also leave this side alone for a while and switch to the lower left corner to see how things develop.
is a fine wedge. Normally W needs to check two ladders before playing C5. Since both ladders favor B in this game, this is really an overplay for W. But the end result was good for W, so B got outplayed here.
is normally just an extension to F5, leaving options to play on either side, depending on how W responds.
is too nice to W, giving up the corner for a side block which is worth very little (given the W stone at C14). B really must play B2 to live in the corner. If W saves four stones with B8, B has a really severe hane at F4 or simply a direct cut at D3 to live. With all outside ladders favoring B, W has no severe counter-attack that I see. The sequence to
gave W too large a corner, for a substantial lead in the game.
started a promising attack, which might have given B a chance to get back into the game. Unfortunately, the next few moves were more defensive than offensive. B must hane at B19 to keep up the pressure. W cannot get two eyes in the corner, so B can provoke a fight. The stray B stones at H15 and K14 might prove valuable if B forces W to run.
in the game is good shape but too slow. Note that if W peeps at this point, B has a tesuji worth knowing to protect the cut while keeping sente.
