I would like to say that I have looked at all the current color themed fairies that you have up and they are beyond my capabilities. I stopped by this one because I felt it was lacking a bit, especially in comparison to the rest of the series.
I do like that you made it less monochromatic than the rest as yellow is easily overpowering. Her hair is well done too. I don't think I could list all the things you did right, but here are a few things I feel you could look at that might improve this piece:
I feel that her dress could be improved a lot. I understand the concept you were going for, but to me the dress is reminiscent of a Victorian couch. I think the dress would look more natural if the tufting was less severe or if you removed the gems and placed them elsewhere as they look like the buttons on tufted couches .
Another point I should mention is her expression. She is neither looking at the viewer, nor looking away - she is simply not looking at the viewer... I wish it would feel more intentional. In my opinion it is not as strong of an expression as your other pieces... the expressions of most of your other art are striking and I feel this fairy missed some of that impact.
The fairy (and the butterflies) also seems somewhat detached from the background, although I'm not sure why. Whereas the other fairies all seem within the scene, she seems in front of the scene.