Congratulations, J.!
My little one was preemie, so when he was 2 months old, he was still just taking about 3 oz every 3 hours (sometimes 2). He started taking 4 oz when he was about 3 months old, IF I'm remembering right.
I have 2 boys, 14 years (that's right....YEARS) apart, but neither one of them ever took an 8 oz bottle of formula. (I was not able to breast feed either one.) However, when they started eating solid foods, I started having a hard time filling those hollow legs of theirs! (and still do!!!) During their first year, both of them seemed to "max out" at 6 oz per bottle.
If you think your son is not getting enough milk at a feeding, go ahead and try adding 1 oz of formula. But be prepared....one feeding he'll want it, and the next, his smaller amount will be enough. How the baby is feeling, his activity level, and (believe it or not) the weather (especially the temperature) will play big roles in how much he eats from feeding to feeding. When he starts teething, his feeding patterns will change; when he's in a growth spurt, his feeding patterns will change. With each hour that passes, his feeding patterns will change. :) Just always be prepared with more formula than you think you will need, and you'll be ok. That's why I always loved using the powdered formula ~ like mom's milk, it never spoils! (unless you've already mixed it) Made it a lot easier for days we weren't at home much, too!
Congratulations, again! (Feel free to call me or email me at ____@____.com if you want. My DH and I have a friend who "just" started at Parker this fall; he's from Stephenville!)