Thanks for posting your question and photo. From what I can see here you have an attractive profile. I don't believe you need a chin implant. You do have a strong jawline and chin. These features are consider attractive. Look at Angelina Jolie or Megan Fox. They both have attractive faces...
"For a double chin, InMode FaceTite with VASERlipo would give you the best result.
With significant neck sagging you would need a facelift / neck lift with muscle tightening (platysmaplasty). At the same time, I would recommend lasers (Fraxel, CO2, Halo, or Erbium) and microneedling RF...
Christopher Kelly, MD (license relinquished) says:
It appears that a significant part of your problem is fat under your chin which will be corrected with liposuction. You may also have some loose skin, which will not be corrected with liposuction and require either a necklift or facelift procedure. Good luck.