Read this site:
www.the-clitoris.com
There are myriad reasons why some women have trouble having orgasms during sex. It could be an emotional problem, or she may have difficulty expressing what she needs -- she might not even know what she wants in bed. Or she might know but can't ask for it.
Three times isn't enough to know much of anything about her, sexually, so take your time. Frankly, concluding that she is "wack"
because she doesn't respond like other women or has a smaller clitoris than they do is immature, especially if you want a fulfilling sexual relationship with this woman. If you're just 'boning' her, then why do you care about her orgasm?
Above all - do NOT say things that might make her feel pressured. Saying "I want you to cum" to a woman who has no trouble in that area is one thing, but she might feel rushed, put on the spot or that she's letting you down if she doesn't have an orgasm. It would always kill the mood for me when a man said that. Don't push her to the point where she'll just fake it!!! I'm not saying that you should just throw up your hands and say "she's not going to cum, so I'll just get mine." I'm saying what Bronzed Goddess said -- There's a lot of pleasure to be had other than just the orgasm. Give her that. And hey, you both might get a surprise...
Thirty minutes is 'forever'? My last man went for HOURS. (God, I'm gonna miss him!!!) But there were still plenty of times when I didn't have an orgasm.