Not happy after mandibular setback for class III malocclusion. I still have a flat face, show more gum and look jowly? (Photos)

Thank you for your question and images. In general my preference is to moves bones forward in the face as setting them back can have an ageing affect. Ideally it would be good to do an in person consultation to really understand what you want to achieve and also examine your face. It is true that the nasal base can widen with a Le Fort I but it really depends on the degree of forward movement and there are always ways to reduce or correct this if it is a concern post surgery. Moving the lower jaw backwards can have an ageing affect and weaken the jaw line but it truly depends on where you start from. A Le Fort I procedure would not have corrected you weak mid face, some surgeon will argue that it does but it truly only influences the upper lip and the area between the base of the nose and the occlusal surface of the maxillary incisors. A genioplasty can be performed after a mandibular setback and is a reasonable option to counter the affects of the setback. It is a complex topic and I think a personal examination would be required before I could suggest anything definitive. 
Regards
Dr Guy Watts

Assuming that the maxilla is going to be left alone, only midface augmentation would be the alternative treatment strategy. You need to think about paranasal-premaxillary-maxillary augmentation not cheek implants. This will create a LeFort 1 like midface augmentation effect. This requires specially design implants to create this unique midface augmentation effect.

 Hi, I have performed many facial shaping procedures using dermal fillers, silastic facial implants (cheek implants, chin implant, lip implants), liposuction and/or facelifts for over 30 years.  From the photos, your cheeks are very flat in the front, the back portion of the jaw line is weak, the upper lip is quite thin and the lips are thin overall.  The nose has a wide nasal tip that is rotated at ~ 115 degrees.  These combine to create an elongated, oval 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 a dermal filler or using cheek implants for a permanent enhancement will create full, round cheeks that will feminize the entire face.  Liposuction can be added to further shape the cheeks and face.
 The back portion of your jaw line is a bit weak and can be augmented, without making your face appear masculine, using precise placement of a dermal filler (I prefer using Restylane Lyft).   I have performed many lip augmentation procedures using dermal fillers or lip implants for over 30 years. From the photos, your upper lip is small compared to your lower.  Following my beauty principles, the upper lip should be approximately 75 % the size of the lower lip for the lips to appear balanced. The lips can be augmented using a dermal filler or a Permalip implant.  the "gummy smile" is best treated with precise placement of Botox.
Dermal filers and lip implants offer a much more reliable volume for augmentation of the lips than permanent fillers or fat injections which are associated with increased, unwanted, side effects.Finally, a Closed Rhinoplasty can reduce and refine the nasal tip while adjusting the rotation if desired.
Hope this helps.