M.K.
Your son sounds healthy and normal! Although you may have heard stories from Moms about how their child "sleeps through the night" from early infancy, this is *not* typical. Furthermore, some Moms and Pediatricians define sleeping "through the night" as 6 hours of sleep without waking. All babies are different, and your son may not be one of these miracle sleepers. And it has nothing to do with putting cereal in the bottle.
A healthy sleep/feeding schedule for infants aged 4 months to 8 months is 2 awakenings for food during a 12-hour sleep period (i.e. 7pm--7am). But the good news is that, come 9 months of age, your baby won't physically need a night feeding (barring any medical issues) and you can wean him off night feedings (with your Pediatrician's go-ahead)! Good luck!