The backlight shouldn't light the face, only the outline of the face in order to separate it from the background, also, you shouldn't have deep shadows with no fill (unless you want them) - you need to move and change your light's power as needed, not blindly follow some diagram.

Just build your lighting setup on light at a time, one method is to start with the key:

1. First take a shot with all the lights off, you should get a completely black picture.

2. Turn on the key, move it around and take test pictures until you like how the light falls on the model (ignore deep shadows).

3. Turn on the fill, aim it at the shadows, set it to low power so it just lifts the shadow a little without drastically changing the light.

4. Turn off the key and fill, turn on accent lights (backlight and/or background) take test shots to see they only light what they are supposed to light (the model should be a completely black), if they light the model move them or change power.

5. now you are ready, turn on all the light and take another test, make any last adjustment if needed and take the shot.

Another method is to start with the fill (especially useful if you use ambient light as fill):

1. place the fill close to the camera so it completely lights the subject but set it to low power - this will determine your darkest shadow - take test shots and adjust until the picture is dark but there aren't any shadows that are too dark.

2. Add the key, adjust it until you get proper exposure.

3. Like before, test accent lights with the key off to make sure they don't light the model