Anxiety issue Dd15

[julesover40]

Hi, looking for some advise re Dd15. She has always been quite reserved, not shy, as communicates well with adults etc. But she has always struggled in friendships, doesn't really like socialising, won't arrange meet ups, frequently Says no when friends ask her out etc. She seems to have a small but nice friendship group so wasn't overly worried. She liked her own company and spends alot of time on her own, reading, drawing, TV etc.

Over the Christmas period, she turned down lots if invites out, and became quite tearful/ anxious about going to a planned activity with a friend, so much so I kept her home and made excuses for her.
Similar thing happened last night, and escalated to her having a complete emotional melt down, sobbing, saying she hated herself, had no friends, feels empty. She also admitted she had attempted self harm last year.
I am completely shocked and devastated that my funny, confidant girl has been feeling like this and didn't feel she could confide in us. I'm also feeling pretty useless that I didn't spot these signs and always thought she was just happy in her own company. My other dds are so social, but everyone's different, so I never pushed her to do anything/be more like her sisters.
Really looking for advice for the best way to help her with anxiety and feel her worth, without steamrollering her.
Feeling like the worst mum in the world, but hoping some wise words here can help x

Your poor dd and poor you. Firstly your not the worse mum in the world children especially teenagers are very good at hiding things. Have you managed to have a chat with her about why she feels this way? Has something happened at school maybe? Has something been said on social media or through texts? I know it's invading her privacy but I would have a look on her phone for any clues, speak with the school to see if anything has changed there and ask them to keep an eye on her. If she won't speak to you or you feel your not getting anything out of her then I'd consider going to the gp for some help especially since she's admitted self-harm. Has she ever been out and come back quiet as though something may have happened and she's bottled it up and now won't go out? Just explain to her that your there for her not there to judge or tell her off for anything and you won't force her to do anything but in order to help her she needs to tell you why she's feeling this way. I really hope you get this sorted but I'd certainly go to the gp if nothing changes

Thank you for your reply. I checked her phone last night and do randomly every now and then, and nothing concerning there. Except that she is very bad at communicating and responding to messages.
I think after a long chat it seems her confidence is shot after covid lockdowns and spending so much time at home just with us. It's like she's lost all her social skills.
Her school seem happy with her, she's doing well academic and has friends she spends break/lunch with but as soon as she comes home she switches off from the outside world.
She satys nothing bad has happened, no one bullying her or being unkind, just normal teen banter, but it seems her self esteem is at rock bottom. I will try to encourage her to meet friends/have them over on a one to one basis, but the thought of parties or going out in groups has her in tears. So upsetting to see x