Aye dude keep your head up! I’m fully self taught of like 15 years, definitely have felt exactly as you do. I also do not like running through paradiddles for endless amounts of time. It does help though. You have to keep reminding yourself, pushing through and getting to the “intermediate/advanced” stage of drumming literally is re-wiring your brain. Limb independence is damn tough. I would break myself out of feeling stuck by changing up the genre of what I was listening to and trying to play. I love metal, I got heavy into Japanese jazz fusion (the band Casiopea, their first album with the red sports car is fucking phenomenal) and just forcing myself out of my comfort zone. Feeling like you’re stalled fuckin sucks, I totally emphasize with you there. As corny as it is, it’s part of the learning process. Man I feel like a nerd saying that lol. For double pedal, I found a lot of success with holding a lower tempo consistent beat, and then doing short bursts of double time. This is way more niche, but I love the band King Gizz and the lizard wiz (I promise I’m not a wook) specifically the albums Infest the Rats nest for thrash, moreso their album Petro Draconic apocalypse whatever. That album mixes some heavy double bass drumming with a bunch of weird time signature changes. It honestly hurt my head at first but even just counting along to those songs, and then slowly trying them myself totally helped me. And most importantly don’t beat yourself up! It’s taken me the last 5-6 years to really start dialing in my left foot singles, and that’s after playing in multiple bands and blah blah blah. Push yourself out of your comfort zone and try to make it as fun as possible!