Hi C.,
So I am a little Type A about things and I keep notebooks for both my children that document when and what they ate, when they slept, and when they had diapers changed...and I've been doing it for both of them since they were born (I know, a little crazy). I checked my daughter's (she's 19 months now), and at your son's age she was getting 5 oz per bottle, 5x a day. She would have a bottle when she woke up (about 6 am), and then a bottle every 3 - 4 hours after that, with the target being that she would have her last bottle at around 8 or 9 pm. Then she'd go to bed around 9 or 9:30. My son is now almost 4 months and he eats more than she did - he weighs more than she did and is longer. He gets 6 oz, 5x a day, same schedule as my daughter. I go by the 3-4 hour rule but I'm flexible with it- if he cries for food earlier, I feed him. If he can go longer, I let him, but never longer than 4.5 hours, b/c then he gets over-hungry and it's a nightmare calming him down (he once threw up a whole bottle b/c he was so over-hungry and gulped it down too quick). What size nipple are you using? Make sure it's not too fast or slow; this can actually make a big difference (I learned the hard way!). Every baby is different but I like schedules; they make the day better for everyone! Hopefully this will help! Oh - the rule of thumb I was told is that the amount of ounces you give per day is roughly 2.5 times your baby's weight, but err on the side of too little and then increase it if you have to. So my son is 13.5 lbs, and 30 oz is a little less that 2.5 times his weight.