You should be fine my sister was the same way with my middle nephew she couldn't keep anything down and lost 30 pounds and my nephew was very healthy weighing 7lbs 7oz
you should be fine I lost 10lbs and then gained 13 and now at 38 weeks im losing weight again. I was worried about it and my midwife told me long as the baby is growing its nothing to worry about. Im also losing weight because I cant hold anything down most days.