Not gaining anything!!

Hope

We have been seen by my ob and the fetal specialist and both are worried because I have not gained but 2 pounds the whole pregnancy and apparently it's all her. She weighs 9 ounces and seems to be healthy. They are monitoring me to see if I gain any weight. They said if I dont start gaining weight then she could have a low birth weight or be born premature! I'm terrified to have another preemie.. has this happened to anyone else?!