She's still so young that she HAS to eat at least two or three times a night. She's breastfed so she only eats as much as she needs and her body is efficient at digesting it... plus her stomach is very tiny so it's not as if she's filling up like a gas tank that you can stretch out for 8 hours.
If you give her cereal in a bottle to keep her asleep rather than allowing her to wake up to feed, that's a real problem. It puts her at higher risk for developing Type 2 Diabetes later on in childhood and adulthood. It puts her at higher risk for obesity as well. But the immediate concerns are that she would be forced to sleep through times when she ought to be waking to eat much-needed feedings for growth and brain development. And the reason that babies stay asleep when they're given cereal in their bottles is because while they're sleeping, the cereal is sitting like a lump in their bellies and not digesting so that they feel full.
Avoid the cereal. Feed her when she wakes and know that it's normal. She could be having a growth spurt and/or making up for not eating well while she was sick. Babies know when their bodies need food and when they need sleep. It's our job to read their cues and not suppress them or teach them to ignore their body's cues.