I think the suggestions for more shadows and highlights is a good one.
That said, this looks like one of mine in the middle stages of completion. Depending on the physical size of the face (scale) there should be several highlight shades between the base color and final highlight and the same (or a few less) for the shadows. What you have is good, but I don't see enough of a change from shadow to highlight. Just mix a couple more highlight and shadow colors and cover smaller areas.
For me this would probably mean adding small amounts of white to the highlight color and applying sparingly and also adding a color like Vallejo Burnt Red to the shadow and likewise, applying sparingly.
You are definitely on the right track. If the new highlights and shadows overpower the face, then create a wash from the base color and apply over the face to tone it down.
Hang in there and continue experimenting.
Cheers,
Ken