I feel that the apples of my cheeks are lacking in fullness and it ages my face beyond my 20 years. What kind of fillers would be appropriate for someone so young?
Voluma or Restalyne Lift will give you subtle changes and are reversible. See an experienced injector.
You photo is very normal for a 20 year old and I would not suggest doing any fillers at your age. Overfilling can alter your appearance and would not look natural.