Without a photo, it is difficult to determine how much filler you would require. Fillers such as Juvederm or Restylane are typically used for the lips and most individuals start with a 1 ml syringe. Laugh lines may require 1 to 2 ml.
As many physicians have previously mentioned, it is impossible to give you an amount of syringes needed without a photograph. On average, two syringes of Juvederm is a good start. Even though you are young, everyone's needs are different despite their age; it has more to do with the amount of volume loss and degree of correction needed. I encourage to you to schedule a consultation and discuss your goals with your provider. They can give you a correct estimate of syringes needed at that time.