From your pictures, I do not think you have hypertrophied masseter muscles, but you would need to be evaluated by a board certified dermatologist or plastic surgeon for complete evaluation. One sign of bruxism (teeth grinding and clenching) is waking up with jaw pain and headaches. If you have this symptom, I would recommend seeing a dentist as you may need a custom mouth guard to protect your teeth from further damage. A mouth guard will not alleviate the painful side effects of Bruxism, so this is where Botox injections into the masseters would be helpful. Keep in mind that if you do get Botox masseter injections, this will reduce the size of the muscle, thereby slimming the jawline. Good luck!