Weak jawline/ultra double chin. What can I do? (Photo)

Neck liposuction is a great option for patients with good skin elasticity and excess fat in the neck and around the jawline. This will remove excess fat and stimulate the skin to contract over time which will improve angulation and definition along the jawline. I recommend seeing an expert for a consultation who can go over this procedure to determine if it will achieve your desired results and the cost of the procedure. 
A chin implant or fillers can improve a weak chin.
I hope this helps!
 

While often chin weakness is the main problem and can be the sole answer for a better definition of the chin and neck, your lower face and neck seems to be influenced by 3 factors, first your lower jaw is receding. Second, your chin is week. Third, you have some extra fat under the chin. An ideal result is going to probably come from combination of orthodontic preparation, lower  jaw advancement, chin advancement (sliding osteotomy) and neck contouring (not suctioning alone) with muscle overlap. However, should you decided against a jaw surgery you will still have very significant improvement in your neck definition and contour from the chin and neck surgery without the osteotomy.   

Weakness of the lower third of the face can result in making the middle third and the upper third seemed out of proportion.  Chin augmentation using temporary fillers is an option as well as chin augmentation with chin implant surgery or possibly a sliding genioplasty to improve contour permanently. In some cases submental or chin liposuction was also required to improve the shape of the chin contour. Be sure to consult with a board certified plastic surgeon and best of luck to you.

Some of the that double chin when tilt your head down is anatomical due to positioning and size of the chin and hyoid bone. The treatment is chin augmentation to slightly lengthen the jaw and improve the profile. A gentle neck liposuction can be helpful as well. Consult a plastic surgeon to discuss the various options and the best way to proceed.

The weak chin is best treated with a chin implant placed through a small incision underneath the chin under local anesthesia. Chin implants are manufactured in a large array of sizes, thicknesses, and shapes. In our practice, we use Implantech brand of solid silicone chin implants with an excellent success rate. The fatty deposits in the neck are best treated with liposuction at the same time. Both procedures can be performed under local or general anesthesia, depending upon the patient's desires. For more information and many before-and-after examples, please see the link and the video below

The difference between your current and ideal jawline/neck pictures is that the chin has more projection and the cervicomental angle is more defined. Ideally it would take a sliding genioplasty which pulls the chin and the neck muscles forward combined with neck liposuction and possible platysmal plication to effect that type of desired chin and neck change.

 Hi, I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  From the photos, your chin is very weak and there is some excess fat and skin under the chin.  When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  
 Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess fat and skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut segments of bone).  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.   I prefer placement of a  silastic chin implant through a small, curved incision under the chin (submental) instead of through the mouth for the following reasons:
*The submental approach is sterile while the intra-oral approach is not.
*The submental approach requires limited dissection as it is much closer to where the chin implant needs to be placed along the center (front) and lower most sections of the chin on each side (where the wings are placed).  The intra-oral approach by contrast requires dissection all the way down the entire section of the chin in order to reach the same areas for chin implant placement.  This leads to several issues in my humble opinion.  The attachment of the chin muscle to the bone must be cut during the tissue dissection, the sensory nerves (mental) and motor nerves (marginal mandibular nerve) that move the muscles of the lips and mouth) are all in much greater jeopardy of injury because of the added dissection required.
*The added areas of dissection with the intra oral approach allows upward migration of the implant as well as an increased risk of nerve injury.  Damage to a sensory nerve will create numbness and or an ache type discomfort while injuring the motor nerve will result in an inability to "lower" the corner of the mouth and lower lip.
Hope this helps.