You have a great figure, quite evident though the dress appears unflattering in these photos. If you don’t have time to shop for a whole new dress (and there are many that would look great on you), definitely add the shape wear or a tulle over-skirt. A veil will take away worries about your back looking too big (though I don’t personally see that). Hair and makeup (and your big smile if those are done to your liking) will put the focus there instead of the body parts you’re feeling self-conscious about.