How can I achieve sharp and very defined jawline like Jessica Alba and Pixee Fox? (photo)

At this stage, from your photo, it appears you would most benefit from some jawline sculpting with fillers or an implant. You are thin with good bone structure. Those are the people that do best with fillers in my opinion. The results are more prominent with less volume required. These days we are able to get great results with the different filler products.  I recommend finding a surgeon that specializes in facial sculpting and being clear with your goals.Hope this helps,Best of luck,DrC

For a more defined jawline to strengthen your profile (and help prevent the dreaded jawline "jowl" sagging), we use injectable fillers like Revanesse Versa - a filler known to limit swelling and give subtle, soft enhancements - or Radiesse. Using a cannula to limit pain and swelling, we inject on the bone in strategic points to get more lift and shaping, resulting in a more contoured lower face and defined, structured jawline. I would suggest getting a formal evaluation with a facial sculpting expert. Best, Dr. Emer

It would be very difficult to give an assessment without any photo at least. Based on your descriptions, a chin lift may be an option. However, you would need an in-person examination for an accurate assessment.