I'd not worry about it. Get as much hydration as you can keep down; when you do eat, eat really WELL, and you should be just fine. In pregnancies past for me, any time I got too hungry, I got sick. It was my body's way of telling me that I needed to eat.
In my last pregnancy, I didn't gain a single pound. After I delivered, I weighed less than when I got pregnant. And, Atticus was my biggest baby--8lbs, 15 ozs. During the first 12 weeks with Attie, I lost almost 30lbs. But, after that, I slowly and carefully gained almost all of it back. The difference was that I was super active and I ate only whole foods.
There is some speculation that an increased nausea during the early parts of pregnancy means that the hormones you need to sustain a pregnancy through the embryonic stage are there in good amounts.
That said, I've not been sick at all during this pregnancy. Honestly, it feels great this way!
Good luck to you, and listen to your body. It will tell you what you need.