The one strap look is so cute! I would say to size down. I ordered down a size based on reviews and I'm glad I did. It is a little snug but I feel secure and know that nothing is going to fall out! ;-) I only gave 4 stars because it is a little hard to get on and off but once its on it fits great. I only worry about trying to get if off when its wet. I would still recommend. It is so flattering and modest yet trendy. I love it!