A baby that is 2 months old AND was a preemie SHOULD be eating every 2 hours. What she's doing is NORMAL and appropriate. She's eating that often because her stomach is tiny and can't hold a lot. If you're offering her cereal already, the reason she might go longer in between feedings is because her digestive system is too immature to digest the cereal and therefore the cereal simply sits there, undigested, and your daughter isn't getting all of the calories she needs. I would be very wary of a pediatrician that tells a mother to give a baby cereal before 4 months old if she isn't seriously refluxing.
What your husband might be able to do for you is increase the formula in each of her day bottles by half an ounce to an ounce. If she can get more calories into her body during the day, she may not need to wake as often at night for a feeding. If she wakes and is hungry, you feed her. Simple as that.