Nice image, I really like it. I did notice some banding in the background, lower left. (Which I think is a software issue mainly) Sometimes I see this better than others as I use a Adobe RGB monitor which having a wider colour gamut picks this up bit easier. A little trick I recently found to help remove this is once you complete the edit, firstly makes sure the image file is 16/bit then make a NEW layer from the various layers you made thus far as is destructive editing and means if it goes wrong you won't loose your work. Then select just the new layer and then go to Filter>Camera Raw Filter, adjust as necessary till it seems to smooth out the banding, to do this play with various sliders to taste. It seems to make the the low key colour transition better.

Great job btw!