Ashley,
My wife has never really enjoyed having her nipples played with too much. They are really sensitive, so light sucking and whole breast rubbing is most enjoyable to her. Meanwhile I enjoy squeezing, pinching and nibbling and that's just not her thing, heh. Some of my ex-girlfriends liked it rough though, so that's where I learned to like it probably. TMI? But there you have it, not everybody's nips "feel good" per se, it seems there's a good range of possible feelings.
And now, a week into hormones, my chest is starting to ache all over. No focused pain or knots forming, just whole breast aching, or a warm sensation maybe, like I pulled the muscles or something. Bumping them or brushing doesn't hurt, but cradling them helps them feel better.