Every person has some degree of facial asymmetry in which one side of the face is smaller or different than the other. This difference is most often bony in origin, meaning our skulls are different from side to side.
This is also totally normal. Even people considered the most attractive, for example Angelina Jolie, have significant asymmetry. Augmenting your looks can be helped by correcting some of the asymmetry but one should respect it as well, because making your jawline bigger to match the other side will throw the dimensions of the side off when it's compared to the cheek or eye on that side.
See a good physician with an understanding of how the face should look before doing anything drastic.