Fat Angie by E.E. Charlton-Trujillo

Angie or as she's known at school, fat Angie, put on weight after her sister at eighteen suddenly joined the army and now is missing presumed dead meanwhile her family fell apart as her dad moved out leaving her with her mum and brother Wang who has turned into a criminal and been in major trouble.
Also, Wang's therapist is dating their mum.

At school, Angie isn't popular and so when new girl KC starts to hang around with her she can't believe it as well as one of the most popular jocks in school Jake standing up for her against a violent bully. Stacey Ann is the worst bully but everyone seems to throw degrading weight comments her way.

KC reveals she knew Angie before moving and knows about her sister, the pair also find themselves having mutual feelings about each other despite Angie being warned by Jake that something's not right about the situation that Angie later ends up in while trying to live up to her sister's sporty history and lose weight too.

This book was amazing, it brought up a lot of mental health issues from PTSD, self harm, borderline personality disorder and behavior disorders too as well as bullying and how it progresses and shows everyone's transparency.