Sleeveless Two-Piece Dress

I'm 5'5", size 6-8 and usually fit pretty standard sizes. I ordered the medium and the buttons would not even begin to close-- they lacked a good two inches or more, and I'm bra size 34 C. Sometimes I'm used to the middle button on a front button item having a bit of a gap but this felt easily two sizes too small. The skirt portion was almost too big, and the elastic wasn't tight enough to sit on my waist, so the front of the skirt sagged. In addition, it's not a true two piece outfit-- the skirt is sewn into the top across the back, making it kind of hard to get into: you have to unbutton the whole front, step into the elastic waist skirt, then pull up and button the vest. It would have been so much easier, and versatile, if they had made it as a true two piece set. I definitely recommend sizing up, but for me, I'm returning this bc the next size might fit on top but then I can't imagine how big the skirt would be. Cute idea, but fit was funky