Old Navy and American Eagle.

American eagle, Abercrombie, pac sun, and hollister are my similarly sized daughter’s favorite stores. They have size 00 jeans which is probably what she needs.

Tysons corner center has all of these stores, FYI.

Aeropostale has about the smallest sizes I've found. American Eagle also carries really small sizes. We've had some good luck with pajama pants at places like Walmart and Gap.

My 11 yo is a similar height and weight. She had good luck w/the smallest size at H&M. It seemed counterintuitive to move to adult sizes when the kids’ 12 waists were so big on her, but she was able to get a waist and length that both fit, more or less. She’s a jeans-only girl though, so we didn’t try anything else.

My 10yo daughter is a little over 5 feet, 87 lbs. She doesn’t appear super thin but we’ve been having trouble finding clothes that fit. Her waist is about 23 inches and hips are 28. She’s looking for pants (doesn’t like jeans) and she would like some PJs but the bottoms always fall down. She has some athleta size 12 but they are verging on too short. Can’t find pajamas anywhere. Suggestions would be appreciated. The shorts that fit best are size 7/8 but they are obviously too short.