Faces seem to go hand in hand with overall body fat. Typically, when someone starts to lose weight, the face is the first place you will see it. If you have a completely toned body, where all your muscles appear to be carved out of wood, "similar to a fitness model", then you have probably reached the point where your face can't get any slimmer.
I have known people who were very thin and had some decent muscle. They would work out constantly. When summer came, they wanted to slim down a bit for it. When they did, they cut their muscle size down by half and tightened everything up even more than before. This was when they got to the point, to where their ribs would show if they stretched out. Or if they bent over, you could see them in their back. To look at before and after photos, they looked anorexic. And yes, it showed in their face dramatically.
Other than becoming skin and bones, there isn't much else you can do if you are thin. Eat an ultra clean diet and exercise regularly. Otherwise, there are plenty of ways to make your face "appear" thinner. I caught an episode of a talk show once, where trying to appear thinner, was the topic. It showed different things that people can do, ways to dress or cut hair, to make them look thinner. Change your hairstyle or wear over sized glasses and sunglasses, and your face will appear much thinner! Good luck!
P.S. You look fine, and you are always gonna be your worst critic. So ask people you can trust to give you an honest answer. You'll never be perfect in your own eyes!