I'm making the assumption that you mean through intercourse, since all orgasms in females are generated via the clitoris, not the vagina. During intercourse it is still the clitoris which is being stimulated by the thrusting motion and/or pressure being applied to it by the movements you're generating.
Many or even most women are unable to orgasm just from having intercourse i.e.; vaginally. It really takes several factors for this to occur. Knowing your body really well, having a partner who can last long enough for you to reach orgasm this way, the correcdt position, being in a relaxed state of mind. Geez the possibilities are downright endless why this may or may not happen!
In my life, I've been able to orgasm this way depending on who I'm with. WIth my first husband, it happened all the time. With my 2nd husband, NEVER. We just weren't a good "fit" that way, he also wasn't good at staying erect long enough to make it happen for me. My current partner and I haven't been together long enough to find out exactly how this will play out yet, but he certainly does last plenty long, and I've been on the verge several times, but haven't crossed over yet. I'm confident that once we learn a bit more about each other this will become a possibility for me again, since I know I'm capable of it.
However, having said all of that, most women only will orgasm through direct clitoral stimulation such as masturbation, or having a partner perform oral or manual sex on them. There is nothing wrong with this; in fact its quite normal. Oh and BTW? Focusing on YOU not HIM, will get you there much quicker too
As long as you are satisfied in the end, I see no reason why you need to concern yourself how you're getting "yours". In the meantime, if it really does bother you enough, with a loving and dedicated partner you certainly can take the time to practice finding postitions which might stimulate you better during intercourse than the ones you are using. This might just be the ticket to paradise you're seeking!