How Many J/cm2 to Successfully Achieve Permanent Hair Removal?

I am type I (pale skin, dark hair) and I have received 2 laser treatments with a diode laser. The area being treated is my bikini area. For the first treatment, the laser was set at 15 J/cm2. Is that too low, or can permanent hair removal be achieved at that fluence? My next treatment the laser was set at 27 J/cm2. Is that a sufficiently high setting? The first time, I was super nervous and much more sensitive to the sensation, so my treatment provider kept it lower. The second time, I could feel it, but it honestly wasn't painful really at all even though the setting was higher. Thank you!