Hi Phoenixdown this is a fantastic portrait especially for your first time! Ok take this with a grain of salt I am still very new to all of this but the main thing that sticks out to me is the forehead. I am also trying to understand this for myself. The values suggest that there is a large lump in the middle of the head. I did a paint over with my best understanding.
Im not sure this is 100% correct but it makes sense in my head. Again I am new and probably also made mistake. Maybe this will help!