Alterations Q

jnk062602

How much can a seamstress let out a dress?  It has 2 layers, and the inside layer is really fitted and tight.  The outer layer is flowy and is not a problem.  But it is also already tight around that band that is below the chest.  I should have ordered a bigger size, but it was when the dr was talking about possibly using clomid and dh and I decided not to do that, so I figured we would have a while to go.  I will be 19 weeks at the wedding.  Is there hope, or do I need to order a new one?