Half a curve

I wanted to wear this white belt from H & M where I could show case it, since it was really the first full-day wearing of it.  The easiest way was to go with contrast.  Having not worn this dress in a long time, I figured it was worth it.  However, the dress just isn't the right shape for me.  While it may look a little more a-line in this picture, it's quite straight, something not great on my rectangle body.  Keeping the top unbuttoned adds an "upper curve" but I couldn't find a way to get a bottom curve.  If only I'd seen Sheila's use of layering shirtdresses first!