Hi Adam , like the others said its really about being persistant and eventually they click. We too have an ESS pup who is 13 weeks and although she knows that she has to toilet outside she still has an occasional accident. If you study them carefully you can pick up on the body language that they need to go toilet...although its usually the 5 seconds you look away that they go

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It sounds like you are doing all the right things. The only thing i would suggest is letting her out every 20 mins when ever she is outside of the crate..ive owned 4 springers and i find that as they tend to be a more excitable breed they do sometimes forget that they need the loo when they are buisy being mad 'springers'!!
Ang.