These are looking so good dude! One thing I'd like to touch on, and you may be feeling it as well, is that you should try to experiment with making your colors more vibrant!
If you have the time, I'd like for you to take the eyedropper and just drag it around on the reference while looking at how the colorwheel changes. And then I'd like for you to do that with your own drawing as well. You'll probably notice that the hue and the saturation flucuates a lot more when using the eyedropper on the reference than when doing it on your own drawing.
One thing to keep in mind while painting is what kind of light sources are playing around in your piece. Most of the time there will be some sort of main lightsource with bouncelight and also light from the atmosphere as long as you're not indoors. However it's an exception here cause it looks like a lot of the light from the atmosphere is getting through the window and the light is bouncing and reflecting all over the place and lighting up the entire scene hence why the background looks very blue even though the material itself looks to be white in true nature.
Just like how the background is affected by all the bounce light, there is a lot of light that is bouncing off the floor and the walls and reflecting it back right at the character making the shadows in the reference appear reddish or even blue in some areas. I really recommend playing around with the colors here to make it pop out! Sorry for the long wall of text..
