This is a game with two life and death problems: top left first, bottom left last.

I failed both but a mistake from my opponent on the second gave me an undeserved victory.

All victories are undeserved.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

84: Note that once you move back to C15, you have decided to give B the corner in exchange for outside influence.
86: It's hard to say what the best move is here, but remember: contact moves for defense, and attack at a distance.
101: Here is where the L&D problem proper begins. But remember, don't be greedy. Killing the corner is very possible; killing D13 is very possible; it's unrealistic to think that you can kill both of them.
106: In general, you want to reduce the eyespace from the outside (e.g., A15, D18) before playing an inside move. That's just good style, and if you read out a kill, you kill however you can. But you always make sure a group is trapped inside before you kill it. A14+D16 is too many cutting points.
132: Cut! You can't let him plow through your shape like a knife through butter. You don't have to stress out too much about F11 because F13 is a good safety valve if those stones get into trouble.
162: G10 looks ugly, but it denies B any chance to make shape.
172: After this point it's impossible to avoid a ko, so you did as well as you could in the lower left (as far as I can read it out).