Kids' Paillette Accent Tiered Tulle Party Dress

My 2 year old daughter wears a 2T in almost everything, she’s very averagely sized. I bought her a size 24month instead of a 2T because the 24m was on sale and hoped it would fit- but it was huge on her! It was about 4 inches too big around her waist, and had large gaps under the arms. I exchanged it for a size 18m which fit her better, although it still had pretty big gaps under the arms. According to the size chart, she should have fit in either a 24m or a 2T. This dress definitely runs larger than the size chart suggests!