I found writing down a list of consequences helped so that when I was at my wits end I wasnt also having to try and thing of the appropriate thing to say. I stuck it on the fridge 😁.
I also used 123 magic, there is a book if you want to read itbut it works something like this
In a calm moment you sit down and explain that there is a new regime as things arent working well between the two of you and you want to improve things because you want to be the best mummy you can be and that means being the boss, because you are the adult, but also training her up so that she is ready to be an adult when she is older
Then say that the next time you ask her to do something and she back chats or doesnt do it, she will get a 1. The second time will be a two, the third time will be a three.
At three there is an automatic consequence (decided before)
Then the counter resets to zero
Really horrible behaviour (like hitting the baby or you) gets an automatic three but be really careful to not use this too often
Then the REALLY important thing is that each time she gets a point, you are calm, you dont argue with her, negotiate, explain etc. you just calmly say “thats a one”
I used to put a yellow cup on top of the fridge for each count my dc had, so it was v clear and visible
The other thing you can do is ask her what parts of her life she wants some choice over..is it what she wears, what she eats, bed time etc? Then see how much leeway you can give her on the things that are most important to her and least important to you
So if clothing is a big trigger. She wants to pick her outfit, you want some oversight as she often picks crazy things. So on a Sunday you both pull out 5 tops and 5 bottoms you are both happy for her to wear that week and she then gets to mix and match them however she chooses, but she has to wear a coat and trainers or wellies if its raining
Hope there is something in this that you can find useful. Often parenting is finding the bits and pieces of other peoples ideas that you like and mixing them all up to work for you