I can remember high school make out sessions where the girls didn't want to go all that far but the boys got so horny they would take the girl's hand and put it on their erection and use it to jerk themselves. It felt so so great & so sexy. Sometimes the girl wouldn't know or didn't know you had an orgasm in their hand till afterwards.
I went through almost exactly the same scenario with a girl in high school. She had her first-time experience giving me the hand job. I'll never forget (or ever hear it again) her remark that "It is so big!" In reality, it was probably the smallest cock she ever touched. It reminds me of another girl who asked "Is that as big as it gets?"
I was very happy as a teenager doing these kind of things with my gf. It was enjoyable and I don't really regret that much that I didn't get pussy until I was 21.