I'm concerned about weight gain...

I haven't gained a single pound, and have actually lost weight. Like 15 pounds of weight. My baby is fine, right on track, and all... My BP and urine is always perfect... but I'm almost half way through this pregnancy and still comfortably wearing a size 0. This can't be normal. I know my morning sickness is making me lose most of it but what can I do to gain some? I know you're supposed to gain, not lose this much.

I eat like my legs are hollow. I literally don't know where it goes... when I'm able to hold food down. But other days I'm so sick that it's hard to keep anything down other than water and Gatorade.

Please help. Let me know what's happening...