Long thin face with no jaw definition and no cheeck bone structure, what can I do? (photos)

​Volume and contouring of the cheeks can be created with well-placed fillers (Voluma, Radiesse, Bellafill) and Sculptra. Implants or fat are alternatives. Botox and radiofrequency can help slim and contour the jawline. Liposuction can help slim the face. Ultherapy, J Plasma and RF treatments can provide skin tightening and lift. I would recommend getting a formal evaluation with a facial sculpting expert. Best, Dr. Emer​

Both implants and fillers in the cheeks can create good results for patients. Both can build up the cheeks and create symmetry. You must balance the pros and cons of each procedure and do what you feel is the best decision for you.
Fillers:
Pros: No downtime Reversible Quick
Cons: Temporary More expensive in long run
Implants Pros: Permanent Great for patients with poor bone structure Less expensive overtime
Negative: Risks associated with surgery Possible infection Downtime
Hope this helps.

  Hi, I have performed many facial shaping procedures using dermal fillers; silastic facial implants for the cheeks, chin, and lips; liposuction and/or facelifts for over 30 years.  From the photos, your cheeks are very flat (actually concave) in the front and the chin is weak.  These combine (as you correctly stated) to create an elongated, thin, rectangularly shaped face.  
 Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  Cheek augmentation with precise anterior (front) placement of a dermal filler or by using silastic cheek implants (for a permanent enhancement) will create full, round cheeks that will feminize the entire face.  Augmenting the "sides" of the cheeks however, will broaden and widen the cheeks and face creating a square shaped face.
 I have performed many Chin Augmentations using chin implants for over 30 years.  A weak chin creates an imbalance making the nose appear larger, the mid face top heavy and the lower face look short that de-emphasizes the lips and allows early formation of a double chin.  Chin augmentation using a chin implant will add projection to the chin creating harmony and balance to the lower face. 
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty.  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.
Hope this helps.