@paul1998,
Hey Paul,
I don't know if your situation is normal or not but I can tell you that I have run into comparable problems at the same age about 10 years ago. Back then I got together with my girlfriend who I had known for some time and had been good friends with before getting closer and closer. So one day things got more serious and I set the mood, put on music lit some candles and prepared our first time having sex together. Everything went fine as I went down on her for the first time which she thoroughly enjoyed - so far so good. When she returned the favor, everything was fine as well. However, when we tried penetration, my trusty wiener, which had worked perfectly fine to that day, simply wouldn't work the way I intended it to and became flaccid inside of her. I had expected to climax quickly, however, not even getting there felt much worse since I also felt that my girlfriend might feel bad, too. We tried a couple of times without much luck.
That said we still had a bit fun but I was really concerned and stressed out, not knowing what to do about it. And to be honest I didn't really get any advice about it or consulted with anyone, which was probably pretty dumb. Anyway, my girlfriend didn't mind that much since my wiener kind of hurt inside of her anyway (not to brag about its size, it's only slightly above average - that's just the way she felt).
Anyway we continued with what we felt good about (oral sex) for the next couple of months until at some point I felt like giving it another shot and everything worked out fine. We knew each other's bodies quite well and I was not stressed anymore. Instead it felt really good. Unfortunately my girlfriend still initially feels pain during penetration but usually the pain doesn't last long. So from what you have written I would say that you have a great partner to ease your stress. There is more to sex than penetration and you seem to enjoy each other's company. It seems that many people, especially men, tend to exaggerate in terms of how much sex they have. In fact I would still want to be with my girlfriend who today is my wife even if we never had sex again - though I am happy that we do. The majority of my single male friends are not looking for a "girl to bang" but a companion who they can cuddle with, come home to and enjoy life with. It seems that you have found such a person and that she has taken your "confession" quite well. I am sure that pleasuring her without you needing to penetrate her won't be a problem and will be rewarding for you as well. Just massage her, kiss her neck, go down on her and so on. Maybe by the time you see how she enjoys your company and "services" you will regain your appetite, too.
And about you not watching porn anymore: There is something like watching too much porn and having no drive anymore, however, generally speaking if you watch porn like once a day or every two days you usually want more sex, not less. The same is true for having sex: if you have sex you'll want more sex.
Put your worries aside, talk to your lady friend about how you like her and that you enjoy being with her. Ask her if she would like to give it a go with you and try out what works best for both of you.