Well done getting the single figures, though Ive got to say that as I read your post I was thinking EEK to your diet but appreciate its each to their own in terms of management. To have eaten pie crusts, chips, crisps and bananas and only need 7u novo to tackle it is astounding to me. In saying that, maybe your background insulin also helped a bit.
Otherwise, must just be that you are more insulin sensitive at night and if you woke to 23 (werent you thirsty as hell, and peeing ?!) then that same 7 might have done nowt. When you took 7, how did you work out it was going to be 7? Presumably you've got a correction dose ratio ie 1u lowers it by x, so if your ratios are correct then its not really too much of surprise it comes back to what it should surely?