I usually wear a medium and although I can wear this one fine, if I wanted it to hang even a little bit, I'd need the large. The teal is very pretty and the fabric is thin, but soft. It held it's shape and knots after washing, so I hung to dry and it's holding up fine.
I saw this shirt in store and thought, what a brilliant idea, classic and modest in front and with edge in the back. I'm a normal sized adult (5.5 / 145) and had to buy the XL, it is well fitted and rather slim than loose. I'm wearing (M/L) in street clothes but this shirt would compare to size S/M in regular street clothes, but obviously not in the dancing world (XL). Therefore you may want to size up when you order this. The shirt fabric material is soft and feels like a real T shirt. It is very comfortable to wear. Not sure how the knots will survive a washing machine, maybe in gentle cycle, it is advised to hand wash. I got the turquoise color and it is very pretty and looks like in the picture.