I know the bewbie problem is there... but, lol, your dress had more pressing problem. So now, if I focus on other part, it would meant that you have finish the dress parts. I always solve the bigger piece, said so months ago~
You shouldn't have any vertical-ish line in between the bewbs IF you are aftering the tubetop bodice.

Okay, now we can discuss, your material, how gloss and matte it should be.