One of the things I have found very helpful from a mix of advice I have received from Portalbob and Deidara is to play songs slightly above your comfort zone for about 30 minutes (after warming up of course) then going back to the songs at your level that you found tricky and see if you can get a better score. With this strategy I moved from barely getting SDGs on 20s to being able to AAA pretty much any 20 (except Warren. f*** that file lol).
Something I tried that honestly helped my reading a ton was using the filter and playing every song I have not played yet in a set difficulty range. For example: I set the filter 22-25 and played all unplayed files. Then I moved to 26-29, etc etc.
I use QW[] as my spread setup and use a speed of 2.75. Not too long ago I was running at 2.5 and the higher speed while sight reading helped me a LOT with improving my level of reading and just general skill.
You and I are very similar in rank, but you are honestly way better than me seeing as you play a lot of upper 30s and low 40s and get some decent scores on them. You should be ranked a little higher than you are, so try filling out your top scores with some clean ones in the high 20-low 30 range. Your rank should spike a good amount.
I am in the process of just improving my knowledge of jumpglut patterns so I have been playing mid 30s a lot since that is where they can be found a lot lol.
Good luck!
You'll be waaaaay ahead of me in rank if you play some slightly easier files and get clean scores on them. I hope the advice I received can help you as well!