To ask for your advice on how to help her

[Rosebel]

Friday afternoon DH had a call from safeguarding officer at DDs college. I was home too so DH put the phone on loudspeaker. DD had told her that she'd been self harming. Not bad enough to cut herself but enough to leave deep scratches on her arm.
Never felt so awful. I feel awful for her because I didn't notice but she's always worn long sleeves and because she didn't even feel able to tell me.
Safeguarding officer said DD came close to telling DH twice but just couldn't. DD used to be very close to me but since I've gone full time we've lost some of that.
DD started hurting herself because of a controlling relationship and I think it may be linked to other changes too.
College has arranged college and I've suggested to her we go to the doctors or she can go on her own if that's more comfortable but she doesn't engage.
I don't want to push her but I don't want to say nothing and then have her think I don't care. Or should I leave it to DH if she feels more comfortable with him?
I've had a constant headache since Friday as I want to help her but I just don't know how.
It's not really AIBU but more what can I do to help

I had a similar call when my DD was in year 11. Her head of community rang me and I was absolutely distraught that I hadn't noticed anything and she'd been doing it for two years since her grandmother died and other traumatic events. She kept it all to herself and didn't utter a word about how she was feeling (maybe she didn't know how to process her thoughts?).
I felt so, so guilty and so ashamed that she didn't feel she could talk to me.
The school sorted counselling for her but then Covid struck.
I suggested going to see our GP or I'd pay for counselling but she didn't want to, so I bought a notebook for her and decorated it and put it in her bedroom door for her to write any thoughts or worries she had that she didn't feel comfortable saying out loud.
Could something like that help? Also obvious telling her you'll always be there for her.
It's awful, I know

her bedroom drawer not door 🙄

Does she open up to you now? I just wish that I had noticed something waa wrong. I'm hoping counselling will help but my fear is her carrying on. Tbh life as a family has been stressed for a few years and despite trying to shield her from it at 16 she obviously picks up on things.
I will try the notebook idea thank-you for the suggestion.

@Rosebel no, not really. It's so hard because I've always told my children that they can talk to me about anything.

She's so insular and usually, I have absolutely no idea how she's feeling. She really doesn't give much away.

She says she doesn't do it now (she had friends at school doing it) and she's at college now but she gets frustrated if I bring it up and ask, so maybe it was a 'fad' that she thought others were doing?

Apparently she didn't tell me because she didn't want to worry or upset me as she/we experienced several 'bereavements'.

Try the notebook and reassure her that you'll always be there for her. Hopefully your DD will be up to reaching out for help.