End of my tether - please help

[snowwhite1]

I have a 3 year old who was trained at Christmas - or so I thought.
She is dry when we are out and about, in the car, at her granny's and all day at nursery.
To the best of my knowledge she has only ever poo'd in the loo once or twice. She either waits for the night time nappy or does it in her pants - neither of which are healthy (the waiting I mean).
At home she often refuses to go to the loo when asked, or does not ask to go and then pees wherever she in in the house and laughs.
Its really frustrating as I know she can do it if she wants to but I have no idea why she is acting this way.
Re the poo issue, I have tried talking to her and asking why she won't use the loo but she doesn't answer the questions or talk about it.
It is very difficult to treat these as accidents when I am not sure that they are.
She has a 15 month old sibling. I cannot imagine that she lacks my attention - could this be it?
Any advice?

Would she go on a potty? Is it possible it's a splashing issue? Some kids don't like cold water shot up their bums when they poo (well who does?)

This won't help you, but it might cheer you up:

try to ignore it. she will be more likely to use the loo if you relax and dont make a big deal. maybe she's actaully GETTING attention from doing this. i know it's easy to say....have been there too.

cheered up by youtube and all set to be more relaxed tomorrow!
Strangely she has never like the potty, but I might try that as well - why not.
Thanks

youtube video - WTF?