I'm 11w with my third and lost 3lbs so far. It's nothing to worry about unless your doctor is concerned. I gained 15lbs with my son and 2lbs with my daughter. My daughter weighed 7lbs 10.8oz.
It's totally normal. You really shouldn't gain much in your first trimester anyway. A lot of women even lose weight in the beginning, though you obviously don't want to try to lose weight. With my first pregnancy I didn't gain any weight and I'm 36 weeks this time and haven't gained a pound. That's not typical either. I was overweight to begin with and ate better while pregnant, but I'm just saying as long as the baby is healthy that's what matters.
It's normal. You're still early. You maybe not gain any weight until 3rd trimester. Don't worry
There could be a couple reasons, the baby only being tiny right now could be one of them. So could morning sickness, appetite changes,eating healthier. Try not to put too much emphasis on your weight. Just eat healthy and take your vitamins and you'll be fine. Your doctor will let you know if they think you aren't gaining enough or too much. Every girl is different, and every pregnancy is different. Perfect example, my last pregnancy I gained 22 lbs, and this pregnancy (I'm still really early- only 12 weeks) I've already lost ten. If your doctor isn't concerned you needn't be :)