A lot of people would love to look younger than they do.
At the age of 19, I can understand how you feel. When you get older you will appreciate your younger look.
For now, you could get a more mature hair style - asked your hair dresser for advice; experiment with make up, and wear clothing that is fashioned for the more mature person.
Best wishes.
I saw this discussed on a TV show, and the doctors said that some people had a thick fat deposit in their cheeks. I think it is a walled fat deposit. There is surgery to remove it, but that's rather extreme for a cosmetic issue that some people would think cute.
The best thing would be if you could appreciate the look you have. It is uniquely you, and a youthful look is good. When you are elderly and the fat in your face is reduced, you won't have that hollow look.
You may be one of those people who look better as you get older.