I can't cum when I'm with my girlfriend only porn does the trick.

I am a 17 year old boy who lives in Denmark. The main reason I joined this site is because I have trouble cumming when I'm with my girlfriend. It actually hadn't happened to me, even once and we have been together almos one year now. The problem however isn't there when I'm watching porn and masturbating by myself. My fear is that I will never be able to cum when I'm with a girl/woman and because of that I really want to stop masturbating and reagain control over myself. I watch porn 6-7 times a week and somethimes even more. It started out when I was 12 years old and has never stopped or been reduced, not even when I had my first intercourse at age 16, porn still felt "better" and more enjoyable. I really need help. I have tried to stop 3 or 4 times before and it has never worked out for more than a couple of days before I started watching porn and tried edging only to find out I just wanted to masturbate even more.

Last time I came while masturbating was the 19. March but since then I have watched porn twice and edging myself. The last time that happened was today. The 21. March. Please, if you read this, help me..

 

My best guess is that it is due to the death grip, I don't really get any form of satisfaction when my dick is in a vagina.. My goal is to go hard mode, I also think that is the best solution! And thank you for your reply. It has been 3-4 days since I last watched porn or masturbated, so far it's really tough and I recently feel the urge to just go watch some porn and ejaculate..