You may be interested in some of Bret Victor's stuff.

I too am a web developer looking to learn more about design. And I too have read Butterick's Practical Typography, Don't Make Me Think, Visual Display of Quantitative Information as well as a few other classics. But I don't think it's made me much better at design. I sense that there are a few "roadblocks". Ie. things I don't know that are preventing me from actually applying the things I learned in reading those books. Any thoughts on this?