Can't Orgasm. How to make my vagina, clit more sensitive during sex?

I am dating a wonderful man but we are having some difficulty in the sex department. He says that sex for him is GREAT, but I have never been able to orgasm. I can't by intercourse and I can't by him stimulating my clit. I can orgasm just fine most times when I am by myself and masturbating. I can tell this is starting to bother him. He wants to make me happy in every way. I can see it makes him feel insecure. He makes comments about how he doesn't do it for me sexually. The truth is that he does, but I just can't orgasm. I am very attracted to him both physically and mentally. So, I was wondering if anyone knows of any safe creams or pills that can help me make myself more sensitive to his touch and his penis. He has recommended to me a product called Stamina RX for women but I am skeptical to take stuff like this without reading about other people who have taken it. Thanks for any help.