Is my chin too small for genioplasty? (Photo)

It would be very rare to not have enough bone to perform a sliding genioplasty. So rare that I have never seen it even in teens with major underdeveloped lower jaws. How much bone you have to work with can be determiend beforehand by a simple x-ray. There never is a concern about losing teeth from a sliding genioplasty. With a bone cut well below the mental nerve exit from the bone, the risk of permanent nerve damage can also be eliminated. 

You should do well with the genioplasty especially if you need chin length.  Permanent nerve or tooth damage is very rare; small chin or not.  Those same risks are still there with a chin implant.  Find a board certified surgeon who is well trained in genioplasty.   Donald R. Nunn MD  Atlanta Plastic Surgeon