Bad behaviour at bed time

Hello all, I have a 3 year old girl who is for the most part a ray of sunshine. She has never really been bad at all or at bed time, she’s not napped in about a year so she’s always ready for bed at 7, she has supper if she wants it then upstairs for bath every other night, jamas, teeth and 2 stories in bed with me or dad. Never been an issue until the past week or so, she has been so naughty, and when I say naughty I mean I’m like gritting my teeth and wanting to pull my hair out because she’s making me so cross. I’m also 22 weeks pregnant so by 7pm after being at work all day my back is in bits i’m knackered and I’m in no position to be wrestling a 3 year old who’s kicking me in the boobs while i’m trying to get her dressed for bed. She’ll be good as gold until she realises it’s bedtime, from the moment you say it’s bed time now, it starts. I’ve even tried just guiding her upstairs and getting the jamas on etc without mentioning the words but once she’s realised, she asks is it bedtime? and then starts. Idk what the naughtiness even is or revolves around, but she runs away at full speed and fights you off if you come near her, won’t get dressed, won’t brush teeth (without literally being held down by one of us whilst the other one dresses/ brushes) and the worst part is she howls with laughter the entire time. Like dying with laughter. I’ve explained look, no one else is laughing. It’s not funny, it’s not a game. We aren’t chasing her or making it something fun so i’m really struggling to understand other than she’s just laughing at the fact she’s making us so cross? The only reasonable consequence we have been able to come up with is no stories. Bad at bedtime = no nice stories at bed time? She doesn’t give a shit when you threaten her with it but when you eventually get her in bed and she realises she’s not having a story she has an absolute meltdown and makes us both feel guilty and we’re finding it super hard. We both work so after long days it’s like hell. Any suggestions or insights into what could be causing? Anyone in the same boat? Do I just have a threenager🫣😭🤦🏻‍♀️