I know that this is so hard. But I think you have some great ideas.
1. spend time with your ds and parents so she'll feel comfortable
2. pump, so she will be able to have the same amount of milk as when your there.
3. You've got a month to work out a way to get your daughters schedule changed, (I understand your not doing this just to go out, but if your plannin g on doing it, now would probably be convienient)
4. Maybe you could split your time up. Go out early, back for bedtime, and back out again?
And like you say, she probably will be a lot better without you there than you think. I know that when I'm in the room, my 15 month old has to be in physical contact with me, but when I'm not where he can see me or hear me, he does great for my parent. The minute I walk back in, he starts screaming if I don't immediatly pick him up
They really know how to play on our insecurities! You will probably be nervous no matter what you decide, so make sure you have a cell phone and can check in when you need to, and if you make sure you can leave whenever you think you need to , you'll probably feel more secure about going! Good luck, momma, and don't forget to have some fun!!