I am 5'10, normally 130 lbs but currently 7.5 months pregnant....needed a great fitted t-shirt dress for a casual dinner and a few other things this summer. I ordered a medium (I'm normally a small but I knew that wouldn't work with the belly) and it's perfect for me at the moment...it is very fitted but that's what I wanted. If you want it to be a little looser, order a size up! It is super body hugging! The fabric is much more substantial than it seems in the pics...which I LOVE because it makes the dress that much more flattering to your body. and it's not see-through at all. It's more than I'd pay for a basic cotton t-shirt dress, but it surprised me how not "basic" it really was. Great quality, highly recommend. Can't wait to wear it when I'm not preggo too!