Some Women Can Cum Easily, Others Have More Difficulty, And Can Only Get An Orgasm Through Manual Stimulation, Others Cannot Get An Orgasm. It Is Not You, It Is Her, But Whatever You Do, Act Responsibly When You Play This Adult Game.
Try finding the g-spot. It's like.. you stick a finger or two in and curl your fingers so it's like you're saying "come here" to someone. Make sure you curl your fingers so that your finger tips are up against where her abs would be, not lower back. Another thing is you might not of been seeing her long enough for her to "trust" you like that. If it's something like that, don't worry, she trusts you as a person, just subconciously she doesn't know you enough to get off. I mean, that's probably it, since she told you she wants to wait for sex. Don't worry, things will get better in time. She's just got to relax.