Escalating behaviour

[constantlyconfused]

DD is 14 she is hormonal and everyones walking on eggshells all the time. She has had a few issues with girls being vile to her but things are fine now she is sociable and has many friends. Anyhow very long story short she has no regards for anything/anyone unless its her friends.She is going from bad to worse at school.She doesn't try ,does very little work and school have told me she is unlikely to get any GCSEs she is rude when they try to help her and is now so far behind its going to take alot of effort on her part to catch up. She is VERY oppositional . At home she is fine till you ask something of her (anything even putting dirty dishes away) then it takes so much asking it ends in an argument. Everything is met with defiance and sanctions/rewards seem to have no impact . Apart from taking her phone.Last week i asked for her phone following a very difficult evening and day at school she refused i gave her plenty of opportunities she refused so i took it. She slapped me not hard but not the point. Maybe i shouldn't have taken her phone from her but she had many opportunities to hand it over . I cried (shock more than hurt) she cried (but for her phone back!). I feel really low about this escalating behaviour she can be the most lovely girl but recently its like a red mist constantly.
I should add she has ADHD but this is new behaviour so for anyone that thinks she can't help it she can. She doesnt seem to care about anything anymore apart from friends and social media .Any advice?! I have tried grounding ,incentive rewards etc This behaviour has escalated quickly and seems to be when shes happy socially she is awful to us and when things go wrong socially she is cuddly and chatty . I don't get it. She has also stopped swimming (she was very good county competitions) as she can't be bothered !

[ChillySundays]

Teenage girls can be vile - I know my DD was (as still is on the odd occasion). I remember people telling me it would get better and it has but that isn't going to help you with the situation.
Has anything changed recently like new set of friends. The dynamics of a new group of friends or even the addition of one new friend might make a difference
You say she is 14 so has she just gone into Y10 so could the start of options/GSCE courses be making her stressed
My DD used to take any kind of stress out on us. I suppose because she could - at the end of the day no one out of the house is going to stand for a teenager shouting at them.
I do think sometimes they can't help it (hormones etc). There are adult women who are vile at certain times of the month.
I don't know what advice to give but sometimes just knowing you aren't the only one. I'm sure there will some posts saying that the post could easily be about their daughter

[summer68]

Constant, you must have been very shocked when your daughter slapped you- that's overstepping the boundaries ( my ds did something similar) nothing justifies her slapping you, certainly not taking her phone. I read on a post here that one parent would phone the phone provider and suspend the phone - worth looking into for the future.
When dc reach their teens something horrible can happen to them, it's VERY difficult to control ( sometimes impossible) . Let me 'reasure you that it's not due to your parenting, don't be afraid to talk to the school. Also get support for you from close friends.
I feel for you but I don't have a "magic" cure a wilful teen will do as they please. When she's nice make the most of it ( try not to hold a grudge) to keep a relationship between you. Big hugs x