I am having a weight problem with my son too. Though he is older, he hadn't put any weight on for 4 months.
Going from 3.4kg at birth to 5.4kg in 3 months doesn't seem to be a problem, isn't that still following a line on the charts? (Just under the 50th percentile?)
Bradyn if his weight and height matched he should be 2-3 kg heavier, but dad is tall and skinny so he is just taking after he dad.
I too have found that there are periods where Bradyn doesn't drink much from a bottle (I was asked to try to add an extra bottle during the day) bubs won't drink if they're not hungry, you just can't force it all you can do is try again later.
My clinic nurse said they only start to worry if the weight gain crosses two lines on the chart, or if they are obviously not thriving (not happy or developing or growing) or they are continuously throwing up after every meal. If your bubs is doing none of these then the best thing you can do is just monitor his weight, unfortunately these days of legal actions some nurses do opt on the side of caution, not necessarily a bad thing though.
Sorry about the essay
Hope I have helped
Oh also I wouldn't start giving food to try and put weight on bubs, it can actually take a while for them to be able to start digesting it, so you'd just be fulling him up with no benefit. Stick with milk. I think there are certain formulas designed to add more weight if it becomes a problem.
Jeninne, WA, Bradyn 24/11/04, #2 Ryan 01/12/06