Is 5 often a difficult age with little girls?

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My DD1 has always been pretty easy. Not angelic but basically happy, kind, humorous, thoughtful and reasonably obedient.

Then she turned 5 in August and started year one in September.

At school she is apparently very good and doing well. At home she is over excitable, she won't follow simple instructions (this morning's request to get dressed was greeted by throwing her clothes in the air while laughing manically), she plays at being immature, she is wilfully naughty. She shouts loudly through breakfast, refuses to stop when asked, runs round the house making more mess than she did aged two, talks in a baby voice even when asked not to, cries the second she is told off (or worse, laughs), she emulates her two year old sister rather than vice versa. It is driving me insane and all our time together is filled with me nagging or shouting.

Is 5 often a difficult age or is it just my DD? TBH this is harder than any previous phase.

Hiya.
I've got two daughters - 7 and 9yrs. They are chalk and cheese. They are really good kids, but I do feel sometimes that I'm chasing their mess constantly. I do ensure they tidy their own mess - but I have resided to the fact that mess and kids go together.
I've noticed with my two that they mimick other behaviours that they see - whether it be their friends or my behaviour! Sometimes my 9 year old can be quite bossy, and it makes me cringe as I can hear myself in her.
We've always had a routine for mornings, but it seems that I constantly have to nag them every morning to do their routine - until two weeks ago when i made a list for them and stuck it on their bedroom wall - works amazingly - they get up, bed made, teeth, wash, dressed etc and even feed the dogs without me asking them to!! May be you should try a list with her where possible and see if that helps.
Could she be jealous of her sister?
Another thing I notice helps my girls behaviour is when i lay down on the bed with one of them, cuddling them, and have a little heart to heart, telling them how much I love them, and what I love about them. Then I'll slip in a comment about their behaviour that I dont like, and they will then generally tell me why they do what they do.
Go easy on her and yourself, give her lots of love and cuddles, let her know mummy loves her, at the end of the day she's not long come out of the toddler stage, she's still a little girl and she will act immature - because that's what she is.

Good luck, keep us posted x