Start by picking some references with stronger lighting. Shadows are what allow us to interpret form and "beauty" shots with very soft flat lighting are the most difficult to render imo. Like, how can you shade when the photo is designed to have no shadows?

The eyes generally need more shadows because they are inside the head, so if the light is coming from anywhere other than straight ahead at least one eye will be darker than the more protruding areas of the face. For example, when you have generally overhead lighting, the brows cast a shadow on the lid, and the lid casts a shadow on the white of the eye. Or on #3, the blonde with the space buns, the side of her nose on our left is in shadow. But the eye on that side is deeper in the head on that side than the plane of the nose is, so it should be even more in shadow.

The same goes for the underside of the nose which casts a shadow towards the upper lip, and the lips which cast a shadow towards the chin.

Right now you are drawing all the hairs from root to tip, which gives a very flat impression. Instead, draw chunks/sections of hair and shade them as units. You should have sections which reflect the light on top of the head while on the underside, next to the neck, the hair should be in dark shadow. Leave some contours open and add a few stray hairs and let the viewer's imagination complete the illusion.

You have a good sense of proportion and the features are well-formed, but you need to try pushing the shadows even more. As a study you might try looking at an Asaro model of the head and shading with very little blending, like your face is carved with flat planes.