Ouch. I'm so sorry that something that should be so easy has to be so difficult.
My best advice is to call the guy tomorrow. Maybe he's got a lot to do and this one fell by the wayside, and your reminder could help. If he's avoiding the issue, you'll make it harder for him to keep avoiding it, and maybe force a decision. The worst that can happen is that nothing will change, so you don't have much to lose (unless there are other factors here).
There's always the emotion card: "My daughter is desperately unhappy and in need of what the AP class could offer, and I'm confused about why the school wants to make her remain so unhappy."
Don't kick yourself. You're doing your best. We all are, and we don't always get our desired outcomes because there's no roadmap, no instruction manual, and no playbook full of cool moves. For the most part, we're all just feeling our way in the dimness. A lot of people here have talked about finding the "least-worst option" as they strive to find an educational environment for their children. They have a really good point. How much can you realistically expect to accomplish (and how much blame should you dump on yourself) if the best you can hope for is somewhat less horrible than all your other choices?
