I don't wear bra when I wear leotard to do ballet class too. I guest is normal not to wear bra gei, as I saw many apa student ar, or dance instrutor, they don't wear underneath the leotard too. As far as 凸點, hence usually the whole ballet class is women, no problem lar....if you are the kind that have really 凸 nipple, I guess you can try to use 乳貼 under the leotard..
Out of yr question, where do u learn ballet ar?? adult ballet???