Op,
Your D states that she leaked in middle school because she was popular, a cheerleader, and big girl on campus. High school got worse, presumably because she is now in a bigger pond and others have zoomed ahead of her while she is maybe standing still so she feels like she was going backwards. Now in college, the pond has gotten bigger still and so it’s even gotten worse.
I guess what I would address is why does she feel like she needs to be popular, in a top sorority, a cheerleader to bolster her self image or self worth? I suspect that maybe her self image may be influenced highly by the movies? I guess that I would stress the importance of learning how to feel comfortable in her own skin and trying to shed some of the images that movies or tc or social media affect her self worth by defining popularity.