Viktoriya this is absolutely crazy hahaha It's incredible!! I think that you nailed the background hahaha I love the idea of the steps, I didn't think about it at the previous stage 
One thing that I could say is that maybe some parts are a bit too dark, like the neck and at the shoulder. Maybe don't go total black but something less.
Sorry I am thinking what Marc could say to you at the stream hahaha
Another thing is that the skin seems a bit "dead". the shading is perfect but maybe you could give a reddish tint to the shadows. You could just twig the shadow layer colors maybe, they seems a bit grey overall. Marc explains it really good in a YouTube video for coloring skin. But legs looks just amazing for me hahah
Last thing, that maybe it's a design choice and nothing to say with that, is that the skirt seems done with a very heavy material, very thick. In the sense that If I would wear it I would have struggles hahah but apart from that I really like the colors and the tiny details of it.
Hope to not being too hard but I do it because I want you to nail the stream and make Marc without words You really deserve it. But they're just tiny things, it's just great as it is right now.
But of course this is just my opinion, maybe I'm wrong in a lot of things and feel free to don't listen to me and keep it as it hahah
