Just a note to clarify what Gummy said:
The size of your belly whilst pregnant does not equate to the size your baby will be. Obviously, you would be hard pressed to find women who barely showed, yet gave birth to 13 pound babies, but it happen.
What you do frequently find, however, is women who were roughly the size of a barn, and gave birth to six-pounders.
There are a lot of factors that play into how big you'll get, where, and when: your frame, your height, your weight, how much water you retain, how much amniotic fluid you produce, how much weight you gain, where and how you're carrying, genetics, and whether you have had previous to-term pregnancies.
An excellent rule of thumb: ask your mom when she started to show with her first pregnancy.
And good luck with whatever you decide, vintage!
Hope this helps,