I think I'm similar to you OP - 5ft 4, size 14, short legs, but really, straight dresses are your friend. They make the lumpy bits look more contained - those ones that kick out at the bum, A line, floaty from waist, whatever, they are HIDEOUS. I can't buy Boden any more, because even when they pretend otherwise in the pics, you get a frock and it has been A-lined completely.
Those Sea Salt ones are indeed frumpy - and they are shockingly expensive for what they are.
I'm watching this with interest though 