Sliding Genioplasty - Full Reversal?

A sliding genioplasty can be reversed though it is not something to be taken lightly. You're still fairly early from your surgery and very likely some of what you're seeing is residual swelling in the area. I would give it time and let the area heal fully before discussing additional surgery to reverse the advancement. You would not want to undergo an additional procedure unnecessarily.

Genioplasty is an operation where the chin bone(or mentum) is cut and moved forward or in any direction and can be used to lengthen or shorten the face depending on how the bone was cut. This may sound extreme but it is the most elegant way to improve the lower facial contours with the added benefit of tightening the neck muscles. Three months is considered "early" post-op and very little can be determined regarding how it will look until 6 months post-op. I would hazard a guess that many of the problems you describe will resolve over the next 3 months including the lower  lip numbness you did not describe but is also very common at this point in the healing process. Early re-operation is rarely indicated unless it is clear that the chin bone has shifted due to a loss of fixation. The best thing you can do for yourself at this point is to make sure your surgeon is aware of your concerns.