@Una, I would be surprised if the 6 didn't work for you. I should have said that I was going by my regular size on bottoms when I said use your upper size. I don't know what I was thinking. I'll stop being coy. I'm wearing a size 6 here. For dresses and tops, that would pretty much be my regular size, although I am often an 8 for dresses because of my ribcage, chest and shoulders. My hips are slimmer than my shoulders, as I know are yours, my IT friend.
@Elizabeth P, it sounds like you have the same body shape as Una and I. I would think the 10 would work for you. Unlike many of the AllSaints dresses, which I find extremely fitted and short, this one fit me and feels about the right looseness for a sweater dress.