Am I feeding my baby enough, should I increase it at night?

My daughter is 7 weeks old. For the past couple weeks she's been eating between 3 and 4 oz every 2 - 3 hours (she rarely goes more than 2 hours in between feedings). She falls asleep a lot during the day when I'm feeding her so she will barely finish 4 oz but at night she'll wake up twice and both times will "suck" the bottle dry. Do you think I should be increasing the amount I give at her middle-of-the-night feedings? When I put her back down she doesn't get upset, she goes right back to sleep but I'm sure she'd eat more if I had more in the bottle. Did anyone increase the amount they gave their babies at night? Is the amount she's eating during the day ok? We visited a friend who had a 1 week old and she was feeding her 3 oz and said she was eating every 3 to 4 hours. I know every baby is different, just wanted to hear other people's stories.