Trouble climaxing

So it's very frustrating that I can only climax through clitoral stimulation and not vaginal. Sex actually does feel AMAZING to me and I love it. It just gets awkward with my sex partner when they ask if I've cum and I say no every time. Or when I want to keep going after they've climaxed because I hadn't yet.. I've only came like 2 times during sex. It's usually just when I'm playing with myself. :/ But those times during sex were very lucky I was in the cowgirl position both times and had my clit stimulated some how while riding. However when ever I try to purposely get there again in that position I can't. Just wondering if anyone else has this issue or any tips (: