Advice on learning design?

Hello.

I've been doing web development on and off (mainly on) for 15 years now - I always have a personal project on the go, and sometimes paid side stuff. But I still feel that visually, my work is normally "average" at best. I'm a developer & computer scientist at heart, I certainly don't have a visual design predisposition.

Over 15 years, I've tried everything from tutorials, to academics literature and theory on design. I try to pay attention to things I like the design of, and I can spot good design, and articulate why it appeals to me. I subscribe to blogs, subs and consume a lot of design related stuff. If someone gives me a design, I can implement it, I think, very well. But I still can't create sites with that visual "wow" factor.

I don't want to resign myself to mediocrity with the excuse that "I'm just not a design person", but I don't know what else to do. I know that by lacking a predisposition towards that sort of thinking, it's going to be more challenging to create beautiful sites, but surely it's not impossible...?

So has anyone got any novel ideas for improving creative design skills in someone who is naturally a "function over form" sort of person (edit: who's been trying all the standard advice for 15 years, with what feels like no progress at all for the past 5 years)?

Thanks.