Depends what you call a big penis.

The first guy I slept with, when I was 17,was about 7inches, as was the second guy I slept with. I enjoyed sex with both of them, but I only orgasmed once with the first guy, and not at all with the second, even though the both these relationships lasted for a while.

I think I was 19 when I learned to orgasm. I was 39 when I met my boyfriend, he is over 10 inches.