OP, I was this teen. But with no school input.
Would not engage with my mother at all because she “just wouldn’t GET it”
I was embarrassed and ashamed of self harming. So embarrassed. I would cover up and wouldn’t let anyone see. I didn’t have a “reason” for doing it that anyone could fix.
I just couldn’t cope with my emotions and the stresses of school, exams, fitting in, mean girls, my appearance, feeling low.. a range of things that teenagers go through. Self harming made me “feel” .. something.
The first time my mum seen marks on me she said “ have you been cutting yourself? Wow if that isn’t attention seeking I don’t know what is..”
The second time she seen she said “aw have you been scratching yourself again” with a smirk. And a dry laugh. Like it was all a joke.
I was never able to open up to her again. And many many years later I’ve never forgotten it, and never will.
And please tread very carefully. The point I’m hoping to make is, without realising, you may not be making it easy for your daughter to open up. (Equally she may just not WANT to) but if she gets the impression you are DESPERATE for a “reason” for her self harm etc, she will close off. Usually it’s a build up of feelings and emotions. And not just a specific thing causing self harm. She is hiding it. So is ashamed.
Try to bond with her, be there for her, open up to her and don’t mention self harm. Don’t look at it, don’t hint at it. Just be there for her for anything. Hopefully one day she may open up.
And I hope it goes away when the teen stress ends. It did for me. 