Long chin/face, crescent shaped. Any suggestions? (photo)

It would be helpful to see a side view picture as well of your face. A reduction genioplasty, particularly of the inverted V design, will make the chin both shorter and more narrow. That will go a long way to wards shortening your long face.

You should have full work up including xrays.  The problem might also be the upper jaw.  When pushing the chin back, the surgeon should be careful so they do not ruin the labiomental fold. Good Luck!