Unfortunately the values are all wrong in this portrait.
I think I’m having the same problem with all the portraits that I’ve done lately in life drawing.
The light side of the face is fine, I know that I’m at the limit of my palette for the lights, I can’t push those any further. It is the shadow side of the face that is the problem, it needs to be darker. Here is the painting with all the color removed and you can see that there is not clear difference between the light and dark side of the face.
I edited the painting in Photoshop by using the burn tool on the shadow side of the face to separate the value closer to how they were on the model.
I think the biggest issue with these portraits is that I’m not squinting enough and I’m not simplifying the head shape. For the next session in life drawing I’m going to focus on the simple shapes of the head and try to correct the value issues.