Is there a way to find/sort my plays, passing plays to be specific, so I can see what worked/didn't work, and when?

I don't see the problem, I think your game plan was just fine! If you must know though, one way to find out is downloading the game log CSV. From there you could filter out when you have the ball and check what plays were run against what defense, vice versa.

I want to get a close look at my passing game, see what is working, and find figure out why it's working, so I can do more of it

To go gameplan and select 1 previous game. It will show you all the plays ran there.

Remember that this is only if you want to review the last game you played.
If you want to review a game that you played say 4 games ago only (for example), the CSV option is your friend.