Part of the problem may well be that you're moving right at the time that she's about to go to university. Going away to university and leaving everything familiar behind is a huge change - it's the time above all when they want to be able to come home to their own room in their own house with their own parents and their own old friends living on the same street, and everything reassuringly exactly the same. She won't be able to put down roots somewhere new in the same way if she's only there for half the year. I remember the hurt one of my university friends expressed when he went home for Christmas and his old bedroom just didn't exist any more - his parents had turned it into the TV room. Another one was very upset because his parents had just divorced in his sixth form year, his mum had moved, and now he was going home and none of his friends lived nearby any more.
Having said all that, a six week sulk is most definitely not on!