Guys are pretty deft at determining what a woman's shape is under all her clothes. So you're not going to be surprising him with what your look like once the naked time starts. If he's attracted to you with your clothes on, he'll be attracted to you with your clothes off.
Please don't get in your head about it. Don't let any uncertainty about your body affect the way you are, either in the bedroom or in the real world. Just live your life, and have sex the way you want to have sex. On top, on the bottom, wearing boxing gloves, all of it is just fine. You'll be just fine, and any guy you're with will have a grand old time in bed with you.