3D-HIFU face lift 2 months post-op, it has made my face very thin and look 10 years older. (Photos)

Since your "facelift" killed off subcutaneous fat, I am not surprised that it has left you look (and it sounds feeling) older than when you started. After a certain age, fat in the face is our friend. It is what keeps things looking lifted and youthful. I would suggest that you make a consultation with a board certified plastic surgeon to discuss strategically replacing some of your lost volume with dermal fillers or fat. 

well, in one picture you are smiling and in one you are not. That makes a bigger difference than your procedure. IMO, HIFU works largely by killing subcutaneous fat, which might be an issue here.