There are things that can be done to give someone a more balanced look to their face. You must ask first however about your self esteem. You would be better served now by seeing a therapist BEFORE having surgery.
Without pictures or examining you in person, it is impossible to give you specific advice. However, there are many procedures which can be done to enhance your cheeks or widen your face. The least invasive procedure would be injection of a dermal filler such as Juvederm, Radiesse or...
It's important to clarify that certain changes in facial soft tissue are a natural part of the aging process, irrespective of weight fluctuations. It's not advisable to pursue plastic surgery solely to influence others' opinions. The primary focus should always be on enhancing your well-being...