Help buying underwear for XXS?

Hi all, my daughter is 5'4" but quite slim (86 lb at last appointment). She is able to find clothes that fit and look great, but is unsure of where to buy underwear - all of her underwear now is from the kids' section at Target and looks pretty juvenile, which is not really fitting with what she wants as a high school student. I just looked on the Victoria Secret site and I honestly think the smallest size would fall right off her. Any recommendations for where to get comfortable, stylish, teen-appropriate underwear? I apologize if this is a weird question!