What is the Cause of this? Long time?

When i started mastribution in early 14s i have to do so fast n hard even if i try to jerk off i cant ejaculate before 20 - 30 min. Yes day by day it becomes habbit and for many year i mastribute just by rubbing penis outside my pant shorts Now i tried every mathod start stop squeeze but nothing seems to be worked. Can any doctm explain me is my penis Become weak? Due to 11 years of mastribution about 2 3 times per week till now or sometime twice in week.. is because my semen becomes thin and very less in quantity? Or any other cause ? I suffered from last 6 7 years... bt at that time i hesitate to tell someone bcuz everyone will make joke out of it. Can i really enjoy that Pleasure and every sex position for long time??