Need advice of veteran players!

So I just finished a POS 1 Phantom Assassin game, had a rough early game into a crazy late game. I feel I played my heart out, but ultimately we lost. Currently a 2k Crusader scrub, so I'm hoping I have some big issues that I can fix with some suggestions and improve my gameplay. Any help would be appreciated!

Match ID: 7329198956
Playing PA POS 1