My boy's the same age and hasn't had nappies at night since January, 8 months on he sleeps through some nights and others he wakes us up for a wee. On the very odd occasion he wakes up having wet himself. I've heard being dry at night has a lot to due with a hormone called vasopressin?? I guess what I'm saying is that it can vary from week to week, month to month. Sounds like your girl is doing great so far. :)