4oz at 3 weeks?

First time mommy here! I have a 3 week old baby and I started giving her 4 oz when she was about 2 weeks, cause 3 just wasn't filling her up; she'd get hungry every hour instead of every few hours.

Usually when I feed her, she eats until she gets to 2 oz, then she stops and I burp her, then she'll eat the last 2. But today I gave her a bottle and she ate the whole 4 oz without taking any breaks, and it's the first time she's done that. Even then, she was showing signs that she's still hungry. Should I ask my doctor about upping it to 5 or should I let it stay at 4?

Just a little background info, she was 7.4 pounds when she was born and she's around 8 lbs now. So she's not a very big baby.

Thanks for the help!