Conventional advise is not going to fly in this case. Most of us would just say "find another psychiatrist!"
I believe that I would call the psychiatrist's office every day until I got a return call. "I called yesterday and left a message for Dr. X. and I haven't heard anything yet. It is very important that I speak with her concerning my daughter's medications. If she is unavailable now, I would like to leave another message." I would do this until you get a call back because the secretary is so embarrased to keep taking your call.
Then, at the next appointment, I would address it in an extremely calm manner. That you understand how thinly she is spread with her case load but you do expect a doctor to call when a patient has a medication question or concern. Is there a problem with that?
Then, I would make monthly appointments as Janet suggested.
You are a year off from moving. I would not wait to work on stabalizing your duaghter. You will have monthly pdco appts. and your pediatrician for emergencies.
I can only imagine how incredibly frustrating this is for you.
Sharon