The first trimester it isn't uncommon to have no appetite due to morning sickness and hormones. Just try getting something small down there a couple times a day and know that in the second trimester you should get your appetite back.
Throughout my pregnancy, I lost a total of almost 20 lbs due to not eating. I had almost no appetite during my first and second trimester. I started getting some appetite back towards the 6th month. Towards the 9th month, I actually gained 3 lbs, most likely when the baby started putting on weight. However, I was considered high risk due to high blood pressure, so I was getting an u/s every 5 weeks. The baby was growing just fine so no one was really concerned. I wouldn't worry too much until the second trimester. As long as you're taking vitamins you should be ok..