Thanks for writing to us,
The weight gain during a normal pregnancy
, is about only 2 to 3 pounds for 1st trimester (1st three months). After that 1pound per every week.
As you are on 16th week of pregnancy , if you gained 7to 8 pounds of weight ,it is normal .
Do routine ultrasound
at least once a trimester , to know your babies condition.
let me know if you have any doubts,