Love this dress so much! If you want it to fit tightly, but a size down.
I got the xs/s and it fits perfect. It's so cozy and cute, and theres no problem wearing a strapless bra with this. If you are in between a medium or the smaller size, I would go smaller. Its not short (although, I am 5 feet tall) and has lots of room to shape with your body.
I love this! Got so many compliments.