This is why rules are made to be broken: Go ahead and center your composition. Give it a strong dark vignette. Blow out the highlights and deaden the dark areas.
You've created an imaginative, infinitely moody, lonely image that beckons the viewer. Outstanding work... I love it!
Seriously though, I really like your Processing lately. It has taken on a grunge feeling that is not too overwhelming. Keeps the photos nice to look at. :) This is perfect. I wouldn't change a thing.
Another photo with a classic feel. Something else for you to try would be to look over your shoulder to give that one last glance. I think that would be cool to see too.
I like it. I wonder what this would have looked like if you had put yourself to the side and given us a view of where you were walking to. Now it seems you're just walking away with no place to go. I like the post processing and those overlays rock.