I purchased this shirt in a large based on reviews, however, I could  have gone with my normal size (Medium). I am 52/130lbs, small chest, round bottom... I usually wear a Small/Medium depending on the item.

Overall, I made it work.  It is super cute, light and breathable.  There are 3 buttons, but I only buttoned one as I was going for a certain look.

I would purchase again and I do recommend!