Am I under feeding my newborn?

I’ve been trying to stick to this 3 hour feeding schedule for my LO(only 7 days old) but I’ve found it really hard to follow it.

My LO will feed on my breast for an hour but sometimes she refuses to fall asleep right away after a feed. By the time she falls back to sleep, another 1 or 2 hours is gone. That means we miss the next schedule by 2 hours. So instead of feeding her 8 times a day, sometimes we only get to feed her 6 times.

Am I under feeding her or what do you guys do to feed your newborns? How do you know if your newborns are fed enough?