Don't worry the baby will get what it needs before you. My first pregnancy I gained 6 lbs. The second I gained 1 lb then lost it the following week. My second was a half a pound bigger than his brother. I am now 12 weeks and haven't gained a thing.
I'm 25 weeks and 6 days. I've gained 2lbs the entire pregnancy. The Dr isn't worried. She says as long as baby is the right weight and size there is nothing to be concerned about. But to put on some weight try adding protein shakes to your diet :).
At 23 weeks, I have only gained a pound, that too in last 4 weeks. But my baby is growing well. I suppose all that cut on coffee and sodas and other junk plus healthy eating is behind that, but so long am eating all the nutrients baby and I need, I am not really worried.
Your baby will be Healthy I never gained an ounce until week 28 I'm now 35 weeks up 8 pounds
I never gained weight until 3rd trimester.
I am 19 weeks with the same problem and my doctor just keeps monitoring the baby. It depends on your original size for how worried they will get. Mine is caused by losing weight due to eating healthier and not drinking soda anymore.