I love the advice Tanza - but how true!
I've found that puppies which leave me fully house trained (usually by their mothers) do often regress in new homes but soon re-learn. If she doesn't pee when she's put outside - take her for a little walk. Always have a word that you use when she does 'perform' when she does go and you'll find this serves you well all her life.
And they regress when they are teethingโฆ totally... some more then others...