My daughter has some of the same issues. She eats only 4 times a day (no dreamfeeding) and has usually 3-6 ounces per bottle, although 6 is rare. About a month ago she was easily taking about 5 ounces per bottle, and instead of increasing, she's slowed down. I had tried "forcing" her to take more as well, and all that got me was thrown up on! :shock:
For a while I really really worried and obsessed about her not getting enough to eat, especially when most books say that for her age/weight she should be eating much more. (Granted, at 4 months she is only 10 pounds as she was 4 pounds at birth.) But for now, she's still gaining weight and seems happy so I try not to worry and trust that she will eat whatever amount she needs to feel full.