The thing we call the 'clitoris' is only the actual head of a much larger organ which circles down both legs and into & over the vulva itself. Speculation is that the so-called G spot is actually a point at which part of the clitoris comes in contact with the pelvic bone. Vibrations set up in the bone structure work on the clit until orgasm is produced. It takes longer than the 'head' because of the passage thru bone. However, if your hands were anywhere near her anus, you were causing the same feeling and the lowest part of the clitoris would have certainly picked up on the movement and caused an orgasm. As you gain more experience, you will notice that touching anywhere around the vagina/vulva areas internally or externally will, with enough time and effort, cause an orgasm. Welcome to sex! Have a continuing conversation with her about it. Remember Casanova's words to women, "I use only my tongue for enjoyable sex, the penis is for making children." Forget you have a cock (except for the masturbation when you get home) and get her to understand that risk free sex is very, very possible! Good luck, dude!