I really do feel for you DD, the transition to secondary can be really tough. Do give her plenty of time before going for drastic options like a move. To move during term can make things worse, as friendship groups would have been established, she won't be familiar with the school and routines and will have her leaning interrupted as different schools teach the curriculum in different sequences.
You've done the right thing in making the pastoral staff aware, perhaps your DD could have an appointment with one, or arrange a chat with her form tutor? Some schools have buddy or mentor systems - could she be paired up with an older student to look after her? Ask her to look for positives in the day, we all remember the negatives, hold onto friendly words from other students, praise from teachers. Maybe take on a more positive role, ask her to look for other students who are looking lonely and talk to them, making someone else feel better makes us feel good.
If no-one knows her, then it's a chance to start afresh, no-one remembers what you were like at primary school, so you can be just who you want to be.
Some of the really confident sounding children may also be struggling, but are hiding it from everyone, they may want to shift away from old friends that they have drifted away from and be looking for new ones.
It can take time to settle in, but as other posters have said, things are usually settled by christmas
I hope you things look up soon
And yes, I am a teacher :)