I've been feeding my DS on demand and there are times when he'll nurse for hours, literally. He seems to want to nurse until he's sound asleep. Right after these long feedings he tends to spit up. He doesn't spit up after his shorter feedings (20-45 min) Is he just using me as a pacifier? I don't want to limit his feeding time but I don't want him to eat until he's sick if he's just looking for comfort. Thoughts or suggestions?