I'm 27, and I have a very round face and chubby cheeks. I want a more defined face (V-shape). What are my options? (Photo)

Thanks for sharing.  I feel to achieve your goals of a more v shaped face, buccal fat pad reduction and botox to the masseter muscle would be appropriate.  Of course an in person exam is required to make a definitive diagnosis and treatment plan.  

I treat this everyday in my practice. You may be a surgical candidate but you do not need surgery for improvement. Properly performed liposuction with energy based devices and physical fat removal will do fantastic to remove the fat, lift the skin, and contour the jawline and give a better taper. I have a significant number of patients who come in from Korea and china for this procedure.  I pretreat everyone with Botox or Dysport before surgery to relax the neck muscles, allowing for better retraction of the skin after surgery. Then after treatment we do skin tightening with Venus Legacy to improve the results and decrease the neck swelling. I suggest you only see an expert for treatment of this area as a meticulous surgeon is required to get great results and complications in this area can be devastating both medically and cosmetically. A new medication that is used to remove chin fat with injections called Kybella may also be an option, as it secondarily allows for skin tightening/lifting as well. A formal consultation is needed to determine what are the best options for you. Best, Dr. Emer. 

By removing buckle that you will only increase the dumpling that you have in your cheeks. The full roundness of your cheek will not be affected. Other than for radical bony alteration of the face there is little that can be offered.