I just want a belly.

18 weeks and 5 days, and I have no belly to show for it. I am still nauseated and throw up often. My doctor hasn't been worried about my weight loss, and says we will make sure everything is okay at the 20 wk anatomy scan. But I really worry I am not getting baby the food she needs because I can't confirm if she is growing or not. I am so jealous of all the December mommas that have beautiful bellies to show.