Do I have lower chin? My face looks curve-shaped. Is there a problem on my jaw or chin? (Photo)

You are referring to a slightly convex facial profile which looks aesthetically better on a female than a male. This can be improved by chin augmentation using either an implant or a sliding genioplasty. There are advantages and disadvantages with either technique.

 The photograph demonstrates a recessive chin profile for which a chin implant can be performed to augment the weak chin. Chin implants are manufactured in a variety of sizes and shapes, are inserted through a submental incision, are composed of Silastic  and can be inserted under local anesthesia. For many examples and more information, please see the link below

You have a slightly divergent profile, which is characterized by small chin.  It can be corrected by having a genioplasty.