Nice observational drawing. I suspect the look you describe comes from the lighting and the dilated pupils. How about a nice light coming from above to one side so that the shadow of the bridge of the nose casts to the root of the nose and the lower limit of the shadow goes 2/3rds of the way to the upper lip? Should give a nice sense of form.
That might indeed work. At present, I am still struggling so mightily just to get the shapes and proportions more or less right that I have little energy left for clever tricks. :-)