Am I suitable for a pre jowl implant? (Photos)

Your thought process is correct with the prejowl implant approach but the key to its success is a properly shaped and sized implant. There is little question that a custom made implant is always the best implant option given your chin-prejowl asymmetry, altered anatomy and the unique aesthetic goals you are trying to achieve. Standard chin-prejowl implants are highly likely to create their own aesthetic problems given that they are standard and your problem is not.

I would humbly agree with Dr Lambros, and add a few other thoughts. Most prejowl implants I know of wrap around the front of the chin. This would advance your chin further, something I would be hesitant to do if I were you.
Overall, I think your mandible is narrow and the "angle" is a bit high, which makes the stuff under your jaw a little more visible and allows the edges of your mouth to extend beyond the natural outline of your face, disrupting the youthful lines of your face.
My goal would be to build the soft tissues of your face up around your mouth to prevent this from happening. One strong consideration would be for a mandibular angle implant. This would give your lower jaw some width and definition. It would by adding the width pair better with the width of your mouth and hide some of the structures of your neck. Fat grafting may be necessary to smooth the transition from the implants and perhaps into your cheeks to give you a bit more volume. Fat grafting is less predictable than filler, but is permanent, easily done if already in the OR, and is a great tool in someone that has a stable weight.
Lastly, you are already beautiful- the sliding genioplasty really made a difference and you should be proud of the way you look! My recommendations are only my thoughts should you wish to pursue further cosmetic surgery. 

I think you are great looking. ask 5 docs you get 5 opinions. This is an area that can be approached a number of ways, the idea is to get some volume along the jawline. I couldn't argue with a chin pre  jowl implant, I don't think they are unstable, the trouble is they are not the right shape, they don't fill the space on the lower side of the jaw.  It is a place to start, though but you might need further shaping with fillers. the shape of your chin is influenced by the shape of your jawline which is considerably longer on your left side in the pictures and always will be. My druthers just on the pictures would be to put in a small chin jowl implant and perfect the shape  with fillers or fat.