Botox 3 times in masseter, is it going to be permanent?

Although 25 uints of Boxtox injected into each muscle is the common starting point in the treatment of hypertrophic masseter muscles,  some patients may require lower or higher doses to achieve the desired effect.  In your case, from your history, it appear that you will require a very low dose of Botox, going forward, to achieve the effect you are seeking.  Don't worry if you feel the effect was greater than what you desired, the muscles should regain their size and strength over the next six to twelve months.  I would suggest you space out the injections from three months to four to six months and decrease the dosage 25% to 50%.  If you don't see the results you would like in three to four weeks your doctor can add additional Botox at that time.  Best wishes.