Exposition: I was a virgin until early this year. A girl I befriended took pity on me after I confided in her. (I am 25, hence the pity.) While I was fooling around with this girl, we were doing various things for one another, just having fun all evening/night/morning/afternoon in her apartment

. I've always been an avid student of sexual techniques (real techniques, not that stuff from pornos), and she taught me a bit more and how to make her cum. After some trial and error, I managed to give her two orgasms over the course of those two days. Yay.
Problem: She had a very hard time making me cum, even though she is very experienced. I thought I was relaxed, I thought I was calm. I had purposely withheld masturbation for a week before meeting up with her so that *ahem* my "delivery" would be more impressive. She tried her hands and oral a couple times each. She tried a full-nude oiled-body-slide massage thing. Nothing. (While she was giving me oral, I actually started to go flaccid!). The first evening, we gave up and resorted to me just masturbating myself on her bed while she kissed me. I came then.
It wasn't until the next afternoon that we finally had straight intercourse and I finally came like I should have.
My concern is that I might have become too insensitive from over a decade of masturbating up to 3-5 times a day. I worry that a future girlfriend might offer oral or a handjob and I'll have to say "sorry, don't bother. It won't work anyway."
I mean, I guess it's better than always being premature, but still.
(By the way, this girl and I are not dating. We agreed it was a one-time thing and we're not seeing each other anymore. Sad, I suppose)