I like TJ Maxx online for dresses. Shipping is not super fast but it would come before your trip. They have some a-line and dropped waist that might work for you. BTW I know what you mean about the seams and big boobs!
Check out Everything Emily Ann on IG. She just posted some target summer dresses.
I don't know your style, but one of my Lilly P resale groups was talking about Belk and they are a hidden gem of more preppy dresses and shipping was fast. I was able to return to a local store, so not sure about return shipping.