SydneyB - is your dd definitely actively feeding for all that time?
my ds sounds like he was very simialr to your dd, but fortunately I got more support from the hospital.
His jaundice came on within 2 days of birth, si it delayed us getting discharged. He also lost a lot of weight in his foirst week, and was sleeping through by 2 weeks, which didn't help his weight gain. With good support from the hospital, who alos lent an electirc breast pump, I was able to get through, waking him up during the night and also giving him alternate feeds of EBM.
Anyway, even once we had decided he was just following his own growth curve (seen by the consultant paediatircian at 6 weeks, who encouraged me to continue breast feeding and to "stop the faff" of expressing), he was still a marathon feeder - my bum used to get sore just from sitting for so long!
Eventually I realsied that a lot of it was "comfort feeding", ie I could easily unlatch him. I started to follow the plicy that if I could unlatch him without "breaking the seal", ie I could easily pull him off my boob without it hurting, then he didn't really need to be feeding. I'd then put him down and get on with something (which might have included some sleep or a bath or something else for Me).
ANd as an aside, despite the counsultant's supprt - I did continue expressing. It was quite a useful "skill" I had acquired (although I gave back the electirc one and used an Avent hand one, which I found less painful), and as I was going back to work at 4 months, it was useful to build up supplies in the freezer. It also meant that if I did want an early night, or to go out, thne dh was able to give the feed instead of me.
In the event, I continued to feed ds for 13 months. He is now 6 and a skinny but healthy averge child.