5. I’m a healthy young woman who enjoys sex in most respects. So why don’t I enjoy having my breast fondled?

This is not uncommon, and it seems unrelated to breast size. Sometimes the reason is too-early development; when a girl’s breast are a social problem for her, she learns to ignore or even hate them. Sometimes the reasons is the too-rough or too-feathery
Way she is touched. And sometimes the reason is simply constitutional-that’s just the way her body is.
Many highly sexual women are uninterested in breast stimulation. As long as you enjoy sex in the other ways, I’d suggest you relax and not worry about “performing adequately” in this one.