First of all you did a great job with the line art itself. It's very successful. I must say that I was never a fan of the Winx style but the translation to your style makes it easier for me to appreciate. I think since you are veering close to realism, it is a lot less forgiving than when you just lay out the flat colors. In the flat colors you can see the line strokes and it makes the work effortless.
I want to highlight the Flora work. I get that you are working with faeries but the lighting is getting to be too overworked. Luminescent wings, I get that. Silky clothing material, yup. But when it comes to the organic surfaces like skin, hair and petals, the way they react to the light makes them look like they are also made of silk.
The spectacular behavior of her legs and face looks too hot especially making the rendering look too overworked. What I have attached is a composite of your line art, flat color and full render and played with the transparency. I personally think that with the skin a little bit more diffused, it makes it look softer.