Are there any books or websites you'd recommend I read to learn more about design instead? I 100% need to learn by doing, but wouldn't it also be good to learn what has already been discovered so I don't have to reinvent the wheel? Or is it best to discover good design on your own?

I learned on my own. If I were to recommend anything to read it would be to find a good book on refactoring or dealing with legacy code.

I read design patterns books when i was younger but in retrospect that was a hindrance more than a help.