On the lower reference, if you look, from the bottom lip to the chin you basically have a straight line, that is likely what is swallowing some of the dimension. I’d say you might get a more compelling model is you exaggerated that angle a little, and maybe even have the chin come out a bit more than in the reference.
The other thing is that the reference is already is a sort of idealization/abstraction of a human face, you your model is an abstraction of an abstraction. You will want to slightly exaggerate some parts to have the overall model look real. Faces aren’t symmetrical and perfect anyway, so a weird chin will probably make it look more right.
After writing this I of course saw you weren’t necessarily looking for further feedback on this project. But maybe something for the next one