I've never had an orgasm and I know it's not that I'm insecure when I'm having sex. I've tried different positions and had more than one sexual partner. I don't know why it is that I can't orgasm. Are all girls able to do so?

Yes all girls are able to orgasm. However, most are not able to orgasm through sex alone. Try oral sex that's the best way for a girl to be able to orgasm. Always works for my wife and then sometimes we'll do oral and when she's close then we'll have sex so that she can orgasm through sex as well but it's kind of a stepping stone to get her started through oral.

most women have to play with their clit or use a vibrator on it.