maxfax/bimax surgery does not correct an overly obtuse chin to neck angle which is what you have. You have soft tissue excess to the anterior neck triangle. That is something in the venue of plastic surgery, in particular an advanced type where they need to work deep to the superficial neck muscles with objective of tightening things up so the soft tissue 'hugs' the outline of the mandible more to form a less obtuse cervical neck angle as in a 'sharper' one.
If Dr. Terino is still in practice, go back there and consult about 'obtuse neck'.