You should wake her and feed her every 2 hours. As she grows and gains weight you can wait longer. Ask your pediatrician if your nervous. Some mothers brag that their baby slept through the night in the first week, but it's not a good idea for your wee one to go that long without food. It's ok for her to start sleeping through the night at 12 weeks.
Good luck mama. I hope you get the sleep you need. Sleep when she sleeps, nobody is going to think you're lazy.
Try feeding her when it's time and if she doesn't want to eat just wait until she starts to cry.
She'll let you know when she is hungry. Enjoy the down time!