Hello Antoine,
Others will be of more help with your nodes than I. But just a word on your comp. If you use a different aspect ratio such as 2.39 (for example) you will have a much more dynamic composition, more theatrical. So even though you are not yet happy with what you have, you would still have something worth showing. Perfect realism is a good goal, but when for whatever reason we don't find it, we should still have something to show after all our hours working. I guess my point is with a little dressing up of the image, you already will have something good for your (portfolio?).