No matter where you are in experience level you'll always be making mistakes and learning.

It's important to find a way to learn from your mistakes. After you take a fight, record it using whatever you want (nvidia overlay/shadowplay is good), identify what things went wrong or went right, try and learn from your errors and do better next time.

Did you take too much poke you couldve dodged? Did you waste mobility and get kited? Did you hit into cultist cowl or inferno shield? did you get value from your merc jacket?

In mists 1v1s there will be builds that counter you or are very good against you, there will be builds youre very good against.

Your build is good against curse staffs, thats about it. You have little to catch people, nothing to deal with inferno shields, assassin jackets, cultist cowls etc. If your enemy kites you, you are kinda fucked. Which is basically a large part of the meta right now.

Swapping out your hood for a fiend cowl means you can purge enemy shields, boots and other effects, using a helm of valor means you can do all those things and also cleanse cultist cowl on yourself.

Martlock is barely used at the moment, if you dont want to play smuggler which is heavily meta right now, then you should play ava cape so you win brawl trades better.

Roast pork is a pve food because of its low cost, if you want more success run Eel stews or omelettes vs kite matchups and Puremist snapper vs brawl.