Thank you bendmeoverbackwards yes I do try to tell her I love her in different ways. I always reply "well too bad because I love you lots" when she tells me she hates me and I am the worst woman in the world! Maybe I am not demonstrative enough though? I don't find it easy at the best of times if I'm honest although I'm 100 times more outwardly affectionate, and I hope, easier to talk to, than my parents were. I try and show her in different ways. I've set her up with a study snack box and put her favourite biscuits in it , or make her favourite cake, or buy her favourite (expensive) charcoal shampoo. She's grateful at the time but she can switch back in a second to being rude again.
And yes I understand that lockdown has been incredibly hard for her. Despite some heroic efforts from individual teachers, her school have not dealt with it well. I think she could be depressed because of it, and I set up sessions with an adolescent counsellor. She went three times and then refused to go again because the woman was apparently "hopeless " and "it didn't help in the slightest".
She is hoping to go to university yes and is trying for quite a difficult subject. Like many of her classmates she is finding study motivation difficult though. She's always liked exams and done really well up to now. But this year has been really hard.
She has a really good relationship with her father but he works long hours and doesn't see as much of her as I do. He is quite indulgent towards her, so he escapes the worst of the conflict and used to think I was exaggerating
During lockdown though he has come in for much more fire himself and is now more understanding.
I feel guilty writing this down and realise that I am painting a really negative picture of her when she has many, many good points and of course I would happily jump in front of a bus for her any day of the week. She is very bright, very quick to understand complicated things, she is funny, determined, very good with animals, very energetic, she has a lot of really lovely friends. So I am hopeful for the future. Or rather, I was, until lockdown happened. Now I'm not so sure as she seems to have lost her way. 
Daphne'smate05 I can definitely identify with a lot of what you are saying 
Sending deep reserves of patience and strength to the op and to all the pps on this thread who are struggling 
Btw, on a "lighter" note I have just discovered that there were no mugs in the kitchen cupboard and have bought 13 down from her room
