While it's exhausting in those first few weeks, it's not unusual to need to feed a newborn baby so frequently. Their tummies are so tiny and empty so quickly that they're never really "full". All this feeding is establishing your supply, and teaching her how to feed. She's probably still exhausted and overwhelmed from her transition to the outside.

I second the pps' advice to try to encourage her to learn the difference between day and night, but this is a journey that won't be fixed with a quick solution, I'm afraid. Just make sure you are able to sleep when she sleeps. Have you considered co-sleeping at all? I could get quite a bit of sleep in the first few weeks of Tom's life particularly, because he would just stay on the boob and I'd just go to sleep.