DD 15's behaviour is frequently awful, mostly to me and her slightly older sister. She cannot cope when things go wrong, flies into a rage easily and never shows remorse for her behaviour. Everything is someone else's fault. The whole family will frequently be on eggshells. She can be violent and verbally savage, especially to her sister who will try her best to stay calm. This isn't a new thing, it's been going on for years. No major issues at school although academically, she struggles and predicted grades aren't great. Homework and revision are done to the bare minimum. She has lots of friends, so no issues socialising and she's polite with others. A few years ago, I had her see a psychologist who said no ADD but signs of autism. She hasn't been tested for this as getting her to that appointment was hell, so not sure if I'd manage another. She spends hours on her phone. Her diet is of poor variety - she's a very picky eater and likes the same foods. Eating out in restaurants is tricky as inevitably, there will be something about her meal that she doesn't like. Currently on a city break and last night she stormed off on the streets after another strop. We eventually found her. Even though she knew I was upset, she smirked and laughed. Honestly, she makes me ill! Any advice would be appreciated.