purple formal dresses

I have a formal event on the 14th and need a dress. I'm a size 20 and 170cm. I'm after a maxi dress, I prefer to cover my arms to below the elbow, I carry most of my weight in the middle so something that camoflages that would be great. Stretch preferred for comfort! A jersey knit singlet style maxi would be great too. I prefer to avoid black if I can, blue is my favourite but I also like brights like red, green and purple. purple formal dresses