Oh my! This is so very well done, I'm impressed you even went for the butterfly!

The only thing I might take notice of is the layering. I think you've depicted the drawing true to form and paid a lot of respect to the reference but as the artist, you can change something if it might make the piece stronger. The place where I see an opportunity would be in the stems near the bottom. Because there is an overlap of the flowers you could also cross the stems to increase the depth of the drawing and add even more of that 3D effect. Because we can't see where the stems cross we kind of lose the information about which flower is in front and which is in back. This is so minor though, I had to be really nit-picky to even find something.

The shading is excellent and your attention to detail and value really pays off. Very nice work!