Do I have chin ptosis? What are my options for fixing it? (photo)

Ptosis implies "falling out" or "sagging".  If you think your chin is sagging it may because you have excess soft tissue.  But, if it mostly happens when you smile it could be an excess of bone.  We can evaluate the situation and then suspend the tissue, reduce the bone, and reshape the area for improvement.  It's all done through the mouth!

Dynamic changes that occur when people animate (contract facial muscles) are difficult to change. It is best to seek improvement for conditions that are present without animating. However, you might want to consider some botox to selected muscles to diminish theireffect when you smile. 

Interesting question. Ptosis is specific, meaning to fall. Your chin tends to fall during smiling. The muscles are pulling it down during activation. Because you are young, a conservative approach should be considered. First consider an injection with a neuromodulator like Xeomin or Botox. This will reduce the muscle pull. The most you would consider is a conservative chin augmentation with an implant. See a surgeon who does this procedure regularly