One big pregnant lady: too big too soon
Everyone is different and every one grows at a different rate. Some moms will show with a belly that sticks huge and straight out and some moms will barely show at all. As long as the baby and uterus are measuring on track there is nothing to be concerned about.
There are many factors that play a role into how big a pregnant woman's belly will get. The size of the mother and her bone structure just to name two. Each woman put on weight in different places. Some moms will add more fat and more fluid weight then other moms. Bloating is also common during pregnancy.
The key to making sure you and your baby are on track is seeing your doctor for regular prenatal care. Your doctor will let you know if they have any concerns and they will let you know if you need to make any changes.