How do I shorten the appearance of my long, thin face? (photos)

By your own description you have described the lower third of your face as narrow and long. This indicates the back part of the jaw is weak (narrow high jaw angles)) and your chin is vertically long and slightly recessed. Changing the lower third of your face can be done with vertically lengthening jaw angle implants and intraoral vertical chin reduction This will provide a facial change of vertical facial shortening and lower facial widening. That combination will provide correction of a long thin face like yours.

The facial growth pattern is such that the lower jaw is 'sloped' steeply leading to a narrow long face appearance. The 'back part' of the lower jaw is shorter than the 'front' so the face looks long. By increasing the height and width of the back of the jawline to a more 'squared' look, the face will look shorter and more balanced. Changing the chin may or may not be necessary to achieve the best continuous balance to the jawline.