With your degree of horizontal chin deficiency you would be best served by a sliding genioplasty. You need at least 10 to12mms of increased horizontal projection and using your own bone to achieve is the best long-term solution.
Defined chin requires chin augmetnation and neck lipo
To get the best results you will likely require a minimum of a chin augmentation (with bone advancement or an implant) as well as neck liposuction or fat reduction to defined a better chin neck angle. Jaw advancement may be recommended if you suffer from a small jaw.
Chin implant candidate for more defined chin and jaw line
A chin implant procedure can accomplish bringing the chin forward for cosmetic purposes to help define the chin and jaw line better. Chin implants are manufactured in a very large variety of sizes and shapes which is best determined at the time of the consultation and examination. The chin implants and the mandible are both three-dimensional structures, so an in-person examination is usually required. In our practice, we use Implantech silastic chin implants for the last 25 years. For more information, diagrams of the implants and many before-and-after examples, please see the link and the video below