Sir,I'm 18 Years Old(male)..i Start Masturbate From 15years Old,in A

Sir,I'm 18 years old(male)..i start masturbate from 15years old,in a day 4/5 times daily and i saw too much porn video!,now my sperm coming out at 10 second!! How can i stop this? And how i control myself for this quick sperm fall???my sex is about 10-15 second,i turn this to 20 minute!!is it POSSIBLE?? Plz tell me plz..when I'll 25 yrs will my marriage life is hangning??? PLEASE HELP ME DOCTOR.