Hair transplant is sometimes a gamble, but you chose one of the best surgeon in the game to do it. I was also scared myself, the surgery itself is not that scary, you are 0 risks. What can be scary is the 'what if' but trust me, the more you will worry about it the more you may be disappointed with the results.
I am not even thinking about anything negative, I know it will look great because I went to Dr.Couto. Peace of mind, no stress, enjoy the journey