Sickness and nutrition

I'm taking Diclegis now and doing the typical saltines/peppermints/ginger ale routine to keep the vomiting to a minimum. But I still can't hardly eat or smell anything without feeling miserable. I'm forcing myself to eat a couple bites here and there, but am worried it's not enough... I'm only eating about a third of my usual calories. I'm taking prenatals before bed so I can at least keep those down. Any advice or reassurance? I know sickness is normal, but at what point should I be concerned about my nutrition?