I recently upgraded from a Yamaha student flute to a Miyazawa. The new flute is amazing and sounds really nice, but I noticed that after the first few days things get a bit difficult. I'm having trouble with the higher notes that were actually easier on my student flute, and at times the Miyazawa feels very strange in my hands- almost like I've forgotten how to hold it. Is this just an issue with me, or is it adjusting to the new flute? I have a chair test coming up along with UIL.
Have you had someone who can play flute - your tutor, maybe, or a trusted colleague - check that there's no mechanical and / or manufacturing issue with the instrument itself? Extremely unlikely, but worth doing to rule that out, as keys and springs can get bent in shipping and handling for example.
Otherwise yes, it's very likely to be you adjusting to the new flute. Every instrument is subtly different, and the initial euphoria of having a better instrument than the one you're used to is giving way to the inevitable tiny adjustments that you are going to have to your technique to get the best out of the new flute.
It's down to our old friend practice, obviously combined with advice from your tutor around specific issues you're facing.
If you've still got your old flute I'd suggest that you do the chair audition on the Yamaha and leave serious work on transferring to the Miyazawa until after the audition. If you haven't got the Yamaha any more then I'm afraid you've got a lot of practice to do before the test.