A young adult (YA) book I read in the late 90s:
The main character is a teenage girl. She lives with her mother and younger sibling. She lives in poverty/school outcast.
Three events from the book:
Something about the younger sibling having a pee accident and the vivid description from the teen
Something about eating cereal for dinner
At one point, her family gets a bag of free clothes, which she is really excited to wear to school even though it’s stained. Might be leather skirt and white sweater?