Denise, I'm late to comment, but I just love 5 on you. It looks like a perfect fit. I mean, perfect! And it looks so elegant and sophisticated on you. Love it with those pumps.
I am a fan of the AllSaints aesthetic but am not in love with any of these dresses on you. I like the cream and olive colors on you. I want #1 to work, but just am not crazy about how it drapes. It's a good idea to try a size up, just to see. FWIW, AllSaints does nothing for my ego, either. I took a much, much bigger size (3 sizes up) from even the larger of my two usual sizes in other brands. And that IS calculating from the "US" size, already. So you just can't pay any heed to the numbers issue.

I didn't read the other responses and I was just ho hum looking through the photos until I got to the Trina Turk Dress. It's not as "cool" of a style as the Allsaints dresses but that color is stunning on you! So I would go with that one as long as the fit it ok.

I like how the Isa looks in this size, but yeesh that sounds like a lot of hassle. Love the TT, though! I have a skirt by TT that I really love; I think the brand loves curves more than AS.

(also, I'm the same height and a good 25 lbs heavier than you now after fussing with meds... you don't look big!)