Buccal fat pad removal or masseter botox? (Photo)

Been on SSRIs for 10 years which means I have clenched my jaw for a decade. I believe I have enlarged masseters. I recently went to the dentist and was told I have noticeable jaw tension. I will be having a mouthguard fitted. I told her I didn't like how the masseters looked but she told me it was actually mostly fat, not muscle in those areas. I have been very underweight from anorexia nervosa and the bulging jawline was still there. But it was also there before SSRIs. Any advice?