Hoping someone can help 
We potty trained my 2.5 yr old a couple of weeks ago - she took to it very quickly and now has no accidents, tells us when she needs to go etc. She's still wearing a nappy for her nap (1-3pm) and overnight (she usually sleeps 8ish to 7ish)
However for the last week I think she's been using the toilet as a stalling tactic at bedtime, and now at nap time too. We put her on the toilet before naps and at bedtime she goes before bath and after her bath.
Without fail she'll say "wee wee poo poo" when she has pyjamas and nappy on so I will take her to the toilet again - a lot of the time she'll do a wee or a poo then too so fair enough.
But this is where it starts - we'll go back into her bedroom and she'll say she wants to go again! I normally will do it once more and be very boring when we're in the bathroom but often she'll be messing around (trying to put her hands down toilet bowl etc) and says she doesn't want to get off and she still needs to go. I'll give her a little while but then I'll take her off (during the day she will go to the toilet as soon as she sits on the toilet so I don't think there's a problem there).
Then the almighty tantrum starts! Screaming, hitting, trying to bang her head .. I have no chance of getting the nappy back on. Eventually she calms down (1 hour usually) but at that point I'm at my wits end.
Can anyone offer any advice on how I can do this differently? I've tried us saying goodnight to the toilet!! I'm hoping it's another one of those stages but I have no clue how long it'll last.
I wondered if I needed to shorten her nap, but we had no problems before this (other than the usual stages of not wanting to go to bed occasionally!) so reluctant to do that too quickly.
Help!!!!