How do I know if my baby is getting enough milk?

Taylor

I’m breastfeeding (with a nipple shield) and I can’t tell if my baby is getting enough to eat. She weighed 6lb 14oz at birth and is down to 6lb 1oz on day 6. The doctor wasn’t really concerned today, but we’re going back in a week for a weight check. She has poopy and wet diapers. When I feed her she falls asleep quickly and is very hard to wake up to finish eating. How can I know if she’s eating enough? Or if I’m producing enough milk