Its very fitted, I rated it as somewhat small.
So it you don't like a body-hugging top order at least 1 size up. I got an XL, I'm 56 150lbs and bustie. Its casual yet sexy (the low neck shows some cleavage) but not slinky evening out sexy. Its sneakers and jeans summer picnic sexy.
I have 3 in white, 1 in yellow, and 1 in orange.  I wear a light weight tank under it because I don't want the outline of my bra to show through.
They wash well, do not shrink if dried on low.