I'm 18 years old. What can I do about my sagging breasts? (photos)

It might be to your advantage to wait until you have kids if they are in your future to have them lifted as you may not be able to breast feed with a lift.

Thank you for your inquiry.  The photo provided does not provide much detail about the breast shape.  There is a wide range in breast appearance, so your breasts might be completely normal for your age and body type.  A breast lift does improve the shape and nipple position but there are permanent scars and risks associated with the surgery.  It might be worthwhile discussing your concerns with your family doctor and get an unbiased opinion whether plastic surgery is of benefit to you.