Lovely! The colors of the background fit so well with the 'cream' color of the skull. And the shadow of the skull is very well done: ten stars for that! But might I suggest that you make the skull a few tones lighter the next time? In comparision with the butterflies, I think that the skull should be more white, not the butterflies (although this may not be really realistic...). I just feel like the skull should be a little more white and look more worn, it seems now a bit like it's a blown-up/fake one.
For the rest the picture looks amazing and you did a great job with it. Congratulations on the DD!