I lost 9 lbs during the first trimester. It is completely normal. You aren't supposed to gain a lot of weight because the baby is so tiny. On kidspot.com they have a pregnancy weight gain chart that goes by your height and pre pregnancy weight. It tells you how much weight most people gain by each week. I'm 8 lbs less that I should be at 25 weeks but my baby is growing and healthy so the doctor said not to worry. 

You aren't supposed to gain more than 1-2 lbs in the first trimester anyway!