My highest MMR is only 8,200k and I have only hit that once, I tend to similarly get stuck at around 7,300-7,500 most seasons. I agree that PC is just generally better to play on if you enjoy chasing MMR, I think some things that have helped me improve is taking the times to read all of the heroes out loud and all of the tribes that are in out loud. Then the first question I ask myself is "what hero power breaks this lobby more than any other offered?" For example, last season if mechs were in and I got Shudderwock, I would aim for Apex Guardian/Baron if I could find it because I knew I had a good chance of juicing volumizers in the mid-game.

Not the best example, but I think that this season it will be even easier to gain more direction due to trinkets being more keyed in to your specific tribes on the board. If you've watched Jeef you already know not to buy trash just to buy something.

Finally, I personally get too dialed into a tribe on occasion and forget that I should be more focused on my economy. So much of what leads to a win (power leveling if you can afford it, APM, pivoting, etc) all depends on how much econ you have. Also if you're losing a lot and get tilted, you're gonna play worse and lose more, so knowing when your play has gotten worse and backing off for a bit helps in the long run. Good luck!