Penis numb during sex. Due to masturbation?

I'm sorry, this is going to be a bit much, but I'm going through a tough time in my life right now because of this, so any help would be VERY appreciated.

I'm a 19 y.o. very fit guy who just got into a relationship in march with the girl/woman (feels weird saying 'woman' at this age) of my dreams and have been regularly having sex (or trying to) since. I was a virgin before this relationship. Side note, I had been masturbating frequently since probably age 15-ish...often once every day (sometimes with porn, but I don't think it ever got bad enough for that to be a factor. Now, porn disgusts me).
Another interesting tidbit is that I seem to be very easily distracted. If I get any sensation at all in another part of my body during sex (tired arms, itch on my leg, etc)  my mind seems to lose focus on what really matters and I struggle to not go soft in her. Very frustrating...could it be ADD?
And yet another important point is that I can't really 'turn on'. It's like my brain has set up a mental barricade, stopping me from feeling the essential emotions. It bothers me because my girlfriend can get turned on from even the littlest of things. I don't know what to do about this one...could be connected to long-term low self-esteem and/or the fact that I haven't been in a relationship in a while.

The problem(s): I have trouble getting/staying hard for her. Pretty much the only thing that gets me hard is my girlfriend straddling me, naked. I've never had trouble getting and staying hard while masturbating, and I randomly get hard doing random everyday things, but when we're naked, it immediately goes soft. Which leads me to some form of anxiety, but I don't consciously FEEL anxious at any time, even during sex. I still believe it must at least be psychological, right? And what do I do about it?

Another problem is that during intercourse, I gradually get numb. I can usually last something like 15-30 minutes before it's so numb I struggle to stay hard/climax. And it's only my member that goes numb, nothing else. Could it be from all the masturbation in my past? Has it killed the nerves in the shaft? if so, how long am I looking at for it to heal?

--Thanks a TON in advance. It means a lot if anyone could help. (and i can give you any additional info if this website allows)

[tommybrady2013]

Hey man,
I read in the Male magazine by a doctor that porn can actually lead men to have difficulty getting hard during intercourse. He recommended quitting cold turkey and not returning to it. I know you've indicated that you're no longer using it. I wonder if it might take some time to not affect you. Do you have to think of porn while you're doing it w/ your girlfriend? If so, porn might have a residue.

Now don't take this the wrong way, and I'm not asking to be rude. Do you he any feeling for the same sex? If so, there's nothing to be ashamed of. I'm wondering if that might have any impact.

  

[cheezisgood]

Yeah, I know how badly porn can effect men when it comes back to reality, but I honestly haven't been even close to bad about using it since maybe high school...something like 3 years ago. Nonetheless, it probably has hurt me at least somewhat. And no, I really haven't tried thinking about porn while with my girlfriend...doubt it'd help. I'd probably hate myself even more if it actually worked haha.

And no. I have put thought into it, and can honestly say I have no attraction toward the same-sex in any way. (and don't worry about it, man. It wasn't taken 'the wrong way') :)

Thanks for the reply!