What's wrong with my chin and how can I fix it? (Photo)

I suggest having multiple in person, consultations with oral surgeons in your community. There are several issues going on with your mandible. Your chin has excessive projection. At the same time, it appears you have a dental overbite collusion with a lack of projection for the back of your mandible.
To make an accurate assessment in this time. She’s an option in your case is a bit complex, and perhaps a bit more than what’s suitable for an online post.
If it bothers you enough to have surgery then contact a few oral surgeon and get proper assessments and recommendations.
Best,
Mats Hagstrom, MD

The soft tissue relies upon the underlying 'hard tissue/bone/teeth' for contours. You appear to have a lower jaw whereby the lower teeth are 'behind' the chin point in profile. Often this relates to the lower jaw being 'overclosed' and the jawline being more 'square'. It is best to consult an orthodontist and Maxillofacial surgeon for this assessment. Failing that, one can consider a genioplasty to alter the height and prominence of the chin relative to the 'fold'/lower lip. It is quite a common issue