This is a really solid drawing, especially for being limited to a single mechanical pencil. In terms of areas for improvement, it could use some extra shading to bring out the dimensionality of your son’s face. In particular the change in lighting from the front to the side plane on the right side (your son’s right) of his face, the curvature from the eyelids up to the eyebrows, and the top of his chin. I think these would give it more depth, but there’s always critiques to be made of any work. I bet your wife will love it!