Meg I just wanted to send you a huge My DD is a shocker (still...sorry) for day sleeps and yep fights me tooth and nail, screaming backarching and yep I have days when i wonder how to enjoy her.
I agree with what a couple of others have said about "relaxing" if you are the smallest bit stressed/frustrated whatever they do pick up on it and use the pram...i go out for her first day sleep and she will just drift off (took a few weeks of "tanties") 99% of the time and if we dont go out or go later than she is off kilter and i can pretty much write off sleep for the day.
I have recently found that reading...my books, DS's books, made up stories...seems to help her drift off...i cradle her and rock slowly and gentle pat the bum while reading and keep my voice at the same volume and she will go to sleep much easier...however sometimes i have to let her sleep in my arms as she has days of absolute bed refusal like today

I hope something works for you soon as i really do know how hard it must be for you atm.