Hi Holly,
Before I start let me tell you I really am no expert on these things but I went through exactly the same with wilson. I think that some nights she is sleeping trough and the nights that she isn't she merely wants attention. Are you closing her crate at night or is it open for her to walk around? I crate train and the crate is closed at night and wilson would, some nights, cry and howl, like you I let him out for the loo and he too had another dog in the room with him but still he persisted!!
After a few days we came to the conclusion that he was wanting attention.
As you said she is a little star all other times and so little stars get praise and cuddles, because she is so good and gets positive attention she wants (or expects) this
on demand!!!
She is still so young and may wake feling bewildered (know that feeling!!) and scared or disorientated and so wants cuddles to reassure. We left wilson and didnt go down at all and he stopped eventually it didnt take long ( a few days for him to realise that we aint comin'!!!)and now if we have the cheek to get up in the night and go into the kitchen he throws us such a filthy look for waking him!!
Also she is a cocker! they are a bit needy!!!
If you are sure she is fine and not hurt or anything I would leave her, if your worried about the neighbours explain the sitch and I'm sure they'll be ok
it wont be for long, ( maybe buy some ear plugs!)
Thats what we did anyway!!