My mum ignores my mental health?

I’ve been struggling with negative, depression-like symptoms for almost a year now. I have previously turned to self harm and sometimes struggle with suicidal thoughts, though I do not self mutilate currently.
I plucked up the courage a few months ago to show my mum my self harm. I got worked up about it, and needed some comfort. Instead my mum thought I was ‘being a teenager’. She told me firmly never to do it again, though I had already stopped at that point. She didn’t check on me, and I had lapsed into it briefly after telling her, though I made myself stop.
I told her once more about how I felt bad about myself, and I was told to ‘put on a happy face.’ My mother took me out to the shops to ‘help me get fresh air’. I have experienced anxiety when going to crowded places (way too many people) and I ended up scratching skin of my hands, for which I was reprimanded.
My feelings have been getting worse, and my self esteem has plummeted to the floor. I know I need to make my mum understand but my anxiety has gone up and I find myself flat-out lying when asked about my day. I need to tell her before I do something stupid.
What should I do?