Would I benefit from a horizontal chin reduction (genioplasty)?

In all of your photos you are smiling to some degree (none with you totally in a relaxed state) and this makes it difficult give you sound advice about treatment. It does not appear that you have an excessive or masculine chin but you may benefit from some re-contouring to diminish the width and possibly the horizontal projection as well. When performed correctly this will allow some degree of soft tissue reduction as well. 

i see that the chin is slightly over projected (coming forward a little too much). This could be because the upper jaw is too far back or the chin is too far forward. Moving the upper jaw forward is more complex than moving the chin back. So reducing the size of the chin may be reasonable idea. Consider a consultation to go over the details.  Best wishes. 

I can see your concerns about a modest excessive horizontal chin projection. There are several techniques for its reduction each with their own advantages and disadvantages. The most effective technique would be a submental approach where a chin pad tuck could be done as well to prevent any risk of ptosis. 

I believe, the issue is the upper jaw being in a back position. It did not grow forward as much. Your orthodontist probably masked the skeletal issue. I would not do anything to your chin. 

You have a very nice profile and while your chin may appear slightly strong due to your jaw position I would leave this alone and would not recommend any surgery. Best regards, Michael V. Elam, M.D.