@OP- Good job of game analysis, rather than just asking other people to tell you what happened. That's the biggest step to improvement.
I would recommend focusing on your opponent's threats more. I find that to be my weakness as well. I get so caught up in attacking and improving my pieces and position I overlook simple threats and attacks. Look for weaknesses in your opponent's pieces and pawn structure and attack them.
Good luck!
Did major 1st game analysis and it disappeared when posting. Cannot redo it all, but my main point was 10...f6?? should be 10...Bg3. White must recapture and regardless if with queen or knight, 11...Nxe4 with virtually unanswerable threats.
I get that Bg3 was the superior response on move 10.. but what's this about Nxe4? there's no piece to capture on e4, and neither of my knights can move to that square... o.o