Idk why no one is mentioning it but with inconsistencies like this, one of the best things you can actually do is improve your decision-making, create favourable engagements for yourself and so on. It wouldn't be surprising if the way you take fights is literally making it harder on yourself to win them, especially if you're getting frustrated with your current performance and stray from your fundamentals. Set yourself up to hit shots, and it will be a lot easier, and you can just grind the rest out through training mods.
Summarized, observe the fights you take and how you take them, including your mouse movements and terrain advantage. Watching other players and looking at what they do and where they are in fights is surprisingly helpful. If you're gonna demo review, I'd recommend watching more demos of better players than of your own, as you'll quickly notice the same, repeated mistakes in your own demos if you excessively watch them. Look past the nice shots and focus on the fight as a whole.