Some help with 5.5 year old

[LadyGAgain]

Hi!
Am looking for some advice.
I have a 5.5 year old DD. She's bright, funny, very intelligent and has had a very settled and happy first year at school.
However at home she needs to be the centre of attention. She is loud, disruptive, talks over us, repeats whatever it is she wants to say over and over (over whatever conversation is happening) until she gets attention. We acknowledge that she wants to speak and that it will be her turn next. We finish our conversation (cut it slightly short) and allow her time to say whatever it was which invariably she makes up on the spot. If her little sister (2) is getting some attention she will interrupt, disrupt her game (which she will happily be playing alone). She wants to be watched - so if reading a book she wants you to watch her reading it. Home life is becoming untenable. I actively am looking for ways to spend time away which is awful I know. We don't smack. I hate shouting but I have been pushed to the edge too many times in the past few weeks. I appreciate she is out of routine but her volume, her constant demands and bad behaviour are really affecting me mentally. I think of myself as high functioning but she's breaking me. I feel like a hopeless parent. I hate the thought that I'm failing her (and the younger one) and I need some help and techniques to manage this situation.
Please can you help me.
Thank you.

Sorry I should have added that 1:1 she is absolutely golden.

Any help? Please!

I can’t help, but following as we are in the same situation. My second daughter actually has a speech delay and I’m sure it’s because DD1 is constantly talking/shouting and doesn’t allow anyone else to get a word in edgeways. She will literally say MUM MUM MUM to get my attention then just say ‘oh sorry I just wanted your attention’!!!

Feeling your pain and still hoping for words of wisdom!

Unless your daughter has a disorder (i.e., this is solely attention seeking behaviour), you need to punish her. Talking over adults? "Honey, Daddy and I are having a discussion. Don't interrupt." If she continues, a six minute time out in her room.

You facilitate the bad behaviour by giving her what she wants - attention. So she has learned that her tactics achieve her goal.

Your daughters should be treated equally. If she is bothering the younger one, again, she needs to be punished with a time out.

Thank you @Winterlife . We use time out regularly and try not to give her attention when she's misbehaving - remove her from the situation (time out) with minimal interaction. She hates timeout but we persevere. And then at the end ask her whether she understands why she was in timeout and then explain what behaviour should be like. She's bright so she knows but her desire to be the centre of attention takes over and so we repeat over and over.

I think you have to keep doing that.

The other thing is that she's obviously jealous of her sibling. Does the younger daughter get more attention? I mean, beyond what is required because of her age? Could you take your daughter out alone, just you and her, for lunch or a snack one day, say, every two weeks or so? You could ask her about her feelings, and how you and Daddy are very sad when she interrupts and misbehaves. You could make that a "tradition" with each of the girls, when the younger one gets older. You could even have your husband take one, you the other, at the same time, giving each of them one on one time with the other parent.

Thanks. The odd thing is that she shows no signs of jealousy. Her and her sibling get on really well together. She is kind and caring towards her.
She has separate mummy time and also daddy time. We go out alone, together. She's bright, happy and settled and doing well at school. Hence our confusion in how to beat manage her when she behaves like this. Baffled!

*best manage her! We don't beat. Ever.