when you supposed to gain weight ??

Brittney
Hey ladies I am a lil curious on when I should be gaining baby weight bc I'm having twins n read I should beshowing  more than a singleton mom to be. I have been through morning sickness since 5/6 weeks. I know I dropped lbs bc I was vomiting at least once a day, but now 16 weeks n I'm at pre pregnancy weight. Appetite slowly is growing but not dramatic difference? Is this normal?