Being honest, I don't know if the degree itself is going to help you. What's going to help you is the networking and getting real-world experience. Perhaps going back to college might help with that, but I also think you could equally get it elsewhere.
When you submit your resume to a large tech company on their job site the chances of it getting to a hiring manager are exceptionally slim. If you actually know the hiring manager - or know somebody who knows the hiring manager - your chances are exponentially higher.
If your background is non-traditional the absolute best thing you can do is seek out and network with other engineers, many of whom will be more than happy to help mentor and provide references for you.
> and see myself as a mediocre developer. So what are your thoughts about returning to college and doing it "the proper way"?
A CS degree doesn't qualify you as a good developer, in the same way that my film degree doesn't qualify me as a good film-maker. I must have done several hundred interviews when I was working at Apple, and I don't think I really paid attention to the candidate's major at all: it was never a good indicator of performance.
I can't tell you whether going back to school for a CS degree is or isn't the right decision: what I can tell you is that if you do go back you should absolutely concentrate on networking, building connections, and getting as much practical dev experience as possible. All of these will be far more valuable to you when it comes to getting a job than the academic content of the degree itself.