Endgame question (you can help)

Hi folks,

Yesterday, I played this game and was kinda happy with it until we got to move 19.

Since it was timed 3/0 and we were both kinda low on the clock already, from move 20 on isn't worth any thoughts. I ended up winning on time, but surely wasn't a good endgame.

• How could I have made it better?
• What main objectives I should have persued after move 19?
• Any specific line suggestions?