I’m worried because the doctor missed half of my scalp (photo)

What was the plan you had with the surgeon? Did you and he discuss leaving the middle free of grafts? Did you have hair in the middle that is not showing here because of the shave? If you were uniformly bald, I would agree that this is not a good plan. You have a finite amount of donor hair so first I want to know what is your total donor supply estimate and how much of it was use for this surgery? That would allow me to determine what could be done in the future in another hair transplant session. Do you have a Personalized Master Plan with your doctor to address now and future issues of balding? This is critical, of course.