Yes, that is normal. Nurse on demand as you know....breastfed babies are often like that. No worries. Some babies feed more than others and have different appetites.
My girl was almost at the breast every 2 hours, 3 max. My son, he was a voracious feeder, and I had a hard time keeping up with his nursing needs, and he WAS truly hungry. And they both grew like weeds. LOL
I would not add cereal to the bottle, go according to your Pediatrician as only he/she would know your baby's full medical/health history.
many times, cereal is added to the bottle as a means to get the baby to sleep through the night for "our" sake, not the baby's sake.
Everyone is different, but giving cereal to make her sleep through the night is one method some parents use. Sometimes, introducing cereal too early, can exacerbate or bring on allergies...as the baby's digestive system/internal organs are still developing...and will still be developing throughout the first year. This is why, there are certain food/dietary recommendations for babies, especially during their first year. The American Academy of Pediatrics, recommends giving "solids" at 6 months of age. Or, it varies per Doctor suggestion, baby's condition or needs. Best to ask your Pediatrician first...
During the first year of life, a baby's primary source of nutrition is from breastmilk/formula. Very important.
Your girl may also be going through a "growth spurt" since she is approaching 6 months of age... .this means, yes, they feed more & more often & more in quantity. So if they are hungry, you'll need to feed them, even if it means waking up during the night. It's a phase and will pass.
This is normal... and not only with your baby. Both my children, and many babies go through this, per their growth, developmental phases, and feeding needs and they grow and change. It is not static. It will change every month, or at every growth spurt and developmental change they go through, both in sleep and feeding needs. Sorry, but yes, they are going through a lot and in their cognitive skills too, and they will wake up.
Also, it could be teething... this wakes them too.
All the best, don't worry, your baby is normal,
~Susan