Sex & orgasms.

Ok, so I really want to have a orgasm but I can't seem to have one. I'm 23 I've been having sex since I was 16 and I've never had one. When I have sex I don't focus on myself I don't relax my main focus is to make my boyfriend cum and to pleasure him. My mind be all over the place during sex lol when I'm having sex I don't think about it. I never masterbated I tried to but I just can't. How did you achieve your first orgasm?