3 month old still falling asleep while eating?

kem717

It seems she gets her best feeds in when I'm nursing her to sleep. When I feed her after a nap, she will eat for 5 minutes never getting a real letdown, sometimes popping on and off. If she eats while falling asleep, I can get 15 minute out of her and a couple letdowns. Normal? She doesn't get cranky unless I keep trying to get her to eat, so I'm not sure if she's frustrated at supply/letdown, just a snacker, or distracted.