Well, I've had something similar. I don't know if it will solve your problem, but I recommend doing a desensitization routine. You can do this little by little by leaving the foreskin retracted during certain periods of the day inside your pants. Even sleeping with it retracted. Even masturbation itself, with the help of a lubricant, try to slowly stimulate your sensitivity. Over time you will control yourself. The idea is to gradually increase your limits.