Will swapping a large chin implant to a medium size make my face look longer? (photo)

There are so many styles and sizes of chin implants, but I find examining the patient in person is the best way to determine which implant is best.  You definitely could remove your current implant and replace it with a smaller one, but you and your surgeon need to decide on which implant would be best for you.  I think there should be a way to augment your chin without making it appear longer.  

Hi, a profile (side) photo would help in the evaluation.  If the chin is currently over projected (by the size large implant) or the implant was placed in a manner that elongates the lower face (chin implant should provide horizontal chin projection at a perpendicular angle to the vertical axis....removing and replacing it with a medium silastic chin implant would offer an improvement. I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  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 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.  
Hope this helps.