oh no way you should quit here!
It is really really great for a first try - wow
If you are using watercolors then you would start light and work dark. For other media start dark and build up to your lights.
It also help if you look at the reference photo in black and white so you can see the values better. If there is no change in value, the face won't bend and it will look FLAT. The biggest mistake beginners make is using a washed out reference photo shot full face! Great portraits have good lighting that accents the shapes of the 3D face. Turning the head a bit helps our features stand out.
You got a good start by using a 3/4 face pose. But you have to find the point on the face where the "lightest light" strikes it. Everything else will grade darker away from this point. That helps the face turn.
You already have your lightest lights but certainly not your darkest darks. The rest of the face falls between these
You could benefit by doing a few "ball" drawings (plenty of videos on you tube). The face is the SAME thing only more feature. But the light will bend and turn on the face the same as the ball. Most portrait artists say they draw "shapes" not an eye or nose or mouth.
Hope this helps.