It can be done, like the wise women here have said I also suggest getting in contact with your local ABA support group for when you need some IRL understanding, encouragement and support - between them all they'll know where you're at
Also, between now and then you will have a far better idea of where your little one's at with feeding, nights and there's time to get her used to a sippy cup. My DS wouldn't take a bottle (till we were bright enough to swap the teat! But by then it didn't matter) and took to a cup much better.
Please don't beat yourself up about needing to return to work - it's bad enough you don't want to return, and as you have to, think about nice things, like how proud your child can be of a mummy who returns to work with helping people