How to make her cum?

Hey so my gal and I have been trying to get her to have an orgasm during sex but have been unsuccessful. We've tried teasing her beforehand but that didn't help much. She said sometimes I hit her g spot but it's really faint for her and does not get more intense. We've tried doggy, cow girl, and missionary. Anyone know a good position for playing with her clit during intercourse? Or one that hits her g-spot intensely? Doggy was too uncomfortable for us.