I'm 14 weeks and I haven't gained yet. I have a strong food aversion to almost everything. Just lost a couple of pounds. I was overweight preconception so my dr. said it's ok as long as I'm getting some food down and keeping it down. She said it's ok if I only gain 10 pounds the whole pregnancy.
I gained a whole 1.8lbs, and then list it between appointments. With my last I lost 22lbs in the first trimester (I started off considerably heavier though). As long as baby is growing alright, nothing to worry about!
I also have gained less than 3 pounds at almost 16 weeks... I have a little extra tummy so I don't think it's a big deal. I am also short, so I think it will work out in the end.