How often should my four month old nurse?

My doctor and I worked out a three hour feeding schedule for my four month old (because she has reflux). But she often sleeps through a feeding during the day and does not wake up at all at night. On average, she eats only 5 or 6 times a day for about 10 minutes each time. She's growing well, she's in the 95th percentile for weight and the 97th for height, but is she eating enough? Should I continue as I am?
Note: I breast feed her exclusively.

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