Can't wake newborn for feeding?

My baby is a week old today and over the last few days she has been very difficult to wake up. She has been sleeping in 3-4 hour increments and only waking to suckle for maybe 10 minutes before passing right back out. I've been attempting to wake her for breast feeding every 2.5-3 hours but she will only wake for a few minutes and barely nurse. I may have gotten maybe one 20 minute feeding sessionin the last 24 hours.

She has a good latch, my milk supply is fairly high, I've actually had to pump to avoid engorgement because she won't wake up enough to eat. Her arms are completely limp when she sleeps and it scares the crap out of me, I have to get her naked or change her diaper or something to make her stir.

Is this normal? She really has me worried as this is the second day she has done nothing but sleep. I know newborns sleep the majority of the day but why is it so impossible to wake her for food? :(

Her rectal temp was 98.5 today so no fever. She has had 4 stools and 7 wet diapers today and doesn't look dehydrated but I dont get how 5-10 minutes barely suckling can keep her full or hydrated especially when she was previously eating in 20-40 minute increments. I also use an Owlet sock at night and her O2 and heart rate are within normal range.

Any other mommies experience this with their newborns? Her next pediatric appointment isn't until Friday but I'm worried that something isn't right.