>I read. I work on side projects. I learn new programs like Sketch, take classes on Udemy and Coursera

Sounds like you are already doing more to improve than most!

>I'm not learning that much on the job anymore, just adding value to the company.

Do you feel like you are often the smartest person in the room where you currently work? If so, time to move some place where that isn't the case. I find working with people more skilled than myself is the fastest way to improve. Sure, your ego will take a hit, but it is worth it for the self-improvement benefits.

However, short of places like Google, I'm not sure how to go about finding a place with more skilled people. Can't know for sure until you are actually working there.