I would say it's perfectly fine .... I started at 110 and currently at 23 weeks only weigh 127ish, the baby measures fine according to the doctor & on this site it will show you the "ideal weight gain" which suprisingly isn't as much as I thought !
With my first I only gained the weight of him and once I gave birth I weighed the Sam as befor I was pregnant. I'm 20 weeks now and have gained 1.5kg. Good luck and I hope you have a healthy happy baby :)
Sounds just fine to me! Your weight gain pretty much depends on how you eat and your body! Everyone is different!
It all deponds on the baby and how much you eat.