H.H.
My 2nd child was very difficult compared to my other 2 kiddos. The tricks that worked for us were swaddling with The Miracle Blanket, naps in Papasan Swing (I know, horrible habit but it worked), white noise machine....as well as sticking to a naptime/bedtime routine!
You didn't mention if she is fussy, gassy, etc.??? This could be a reason for her not sleeping well.
Best of luck! You both need some sleep....I remember those days/nights :(