Post hair transplant procedure concern - frontal area where regrowth is much slower? (photos)

Hello. My name is Branislav, I live in China. I had hair transplant procedure on January first this year, 2800, FUE. There is a good progress, no doubt, but there is a place in frontal area where regrowth is much slower. There are small hairs coming out, but I have an impressions I've been looking at the same picture for months now. It simply doesn't fill in! Hospital staff said everything was going fine. What do you think? I appreciate your answers. Thank you.