Hi Mommies, I have a skinny little daughter who is almost 2.5 and I think she is ready for some potty training. However, I cannot find underwear that will stay up on her. She wears 18 month size mostly and many of her shorts are 12 month size. She is average height but a skinny little thing with no butt - certainly not my shape! Anyhow, does anyone know where they sell "big girl" underwear in 18 month size? I can't seem to find them anywhere.