Overtired...

My sweet little is three and a half weeks old. She gets overtired so easily and then we have to pull out all the stops to finally get her to sleep. We do try to lay her down or rock her to sleep as soon as she shows sleepy cues but that doesn't seem to be helping. She sleeps for a two hour stretch maybe once in a 24 hour period (if my husband or I holds her the entire time she will stay asleep this long). Usually she doesn't sleep more than an hour at a time, day or night and wakes easily when we lay her down. We have tried white noise, blackout curtains, bath before bedtime, swaddling, singing, basically everything we have been told should get a newborn to sleep! Does anyone have crazy tricks to get her to sleep, or even just advice on how to survive this phase?