No weight gain at 16 weeks.

I heard this isn't uncommon.. And it's probably not something to worry about. I heard it depends on pre preg weight.. I was 135 before preg.. 5'6". I've fluctuated from 140 to 132. 132 being most recent. Though that may be because I just threw up everything I ate today (which is BC I skipped my diclegis BC I ran out). Can anyone relate? I'm worried this may be harmful.