^^ Um, from what I have read, G-spot orgasms are still due to the clitoris - it's thought that the two are connected somehow, but it's not entirely separate of a clitoral orgasm. In fact, I think the last study that I read stated that less than half of women could achieve vaginal orgasm, although how much of that is due from just not knowing where to find it is up in the air. But that seems to ring true - while I definitely have had a G-spot orgasm, I have a lot of friends that say they're unable to.
Also, the idea that some women can only achieve orgasm with the right male is something that I've NEVER heard before, and I've done a good amount of reading on human sexuality. It reeks of misogyny, and I can find absolutely no studies that verify that. It also doesn't make any sense logically...I dunno, but please don't take that idea to heart.
Anyway, yeah, you sound rather young. I mean, perhaps I was just an especially self-exploratory little 'un, but I'm pretty sure I had my first orgasm around the age of 10. Believe me, you'll know when it happens. Do you feel a build-up of sensation at all, even if it never fully reaches its apex? I know at least since I started on anti-depressants, achieving orgasm has been significantly more difficult (although it seems to last longer and be more intense when I do get there...), but I can still feel pleasure down there, I just have a hard time climaxing. But yeah, I'd recommend that you experiment both by yourself and with a partner, if you have one. Female orgasms are a bit more complicated than male ones, which has its ups and downs X) But figuring out how to get there successfully will obviously be a huge improvement to your sex life.