I seem to put most of my weight on in the first tri, this is my 3rd and each time I start freaking out because I gain weight within the first few weeks! it slows down for me from about 17weeks and then I only gain a few kgs till the end BUT I have to watch I don't use the pregnancy as an excuse to over indulge because i've found it hard to loose the excess weight after baby's born.
I do think it has alot to do with your bmi as I'm only 5ft and average about 13kgs for each pgcy. So far I've gained 7kgs, I gained 6kgs in the first trimester and just 1kg till now (24wks).
I've learn't to just listen to what my body is telling me if I feel too full after meals I know I've over done it and if I'm starving all day and can't seem to get enough food then I know to just go with it as it's pbly a growth spurt and within a few days it slows down again.