Have you tried lunesta? It is supposed to be in and out of your body faster than ambien. Like all sleeping pills it only worked a few days for me but my metabolism is weird and you don't need it every night which matters too I'm sure. I think that it's pretty much cleared your system in 6 hours if I remember right.

Also you have a lot of good sleep hygiene stuff in place but when you can't sleep do you just lay there or do you get up and go to another room? Sometimes that can help reset things, just go and do something calm and soothing like read a book (the paper kind, no lighting on a reader or computer), drink some herbal tea, warm milk (I like it although I know most people think ewww), whatever you can do and try again in 20-30 minutes when you feel relaxed. Otherwise you train yourself to be anxious when you see your bed.