Some thoughts:
: Because white played high, this is a bit soft. The 2 space high pincer is typical, though it can be complicated. The one space low may also work. Pincering is a good choice in general here. The rest of the exchange seems reasonable for black to me.
: It may be worth considering splitting the left or approaching this stone from the left, since white has a lot of potential on the left, but the topside potential is limited by black's low stone at P17. Through
seems good for black.
seems really slow. The corner group is alive and doesn't need any help right now. Better to approach the bottom left directly, or play another big move like that. At
trading the rest of the side for the corner is not big enough, I think, and you could instead consider the 3-3 point or C4 to gouge out the corner or keep white small there.
At
, C9 attacks white's shape. If white takes E8, black takes C8 to peep and connect under anytime. If white takes C8, black takes E8 to peep, and if white takes D8, you can take D10 and leave white heavy with an empty triangle to boot.
At
you may want to peep at G10 first. It's hard to attack this group now, though, because white can play B10 to live at any time. It's worth considering if there's a good black invasion into the lower left corner now that black is strong there.
Later, around
white is trying to make sabaki here. With
to
, though, black takes a vacation from the fight, and lets white get two moves in a row locally, so black fails to benefit. Another option, at
is to fill at R15, and if white lives in the corner, just control the side stone with P10 as a follow-up.
is an odd place to resign, as white was already alive here. Black also has decent center potential, with a move or two around K5. There's still a decent reduction of the bottom left corner left, and the top is wide open to turn a lot of that into dame. The game certainly look playable to me.
to
there is a ladder, but unfortunately it is white's three stones that are caught in it after one move. I think black's fight should be favourable if white goes the other way as well, so I'm inclined to think the double hane may be an overplay.
builds a moyo and that's it. Good moyos are built while doing something else. 
invades because White has his hands free to do so. While attacking the invasion, your wall becomes stronger but it has no purpose towards the bottom.
It's possible there's something I missed, though! 