I don't consider 12-14 plus size but I know some designers do and perhaps they do more in France as they are smaller there than average US size. Also, some stores touted as plus-size do start about US size 10-12 (like Marina Rinaldi), as well as some designer plus-size lines. I thought daph's friend was making that comment since she said there are no large sizes and she wears 12 (which is even slim for someone tall, that's the size Princess Diana wore, or a 10 in UK). In French stores, 12-14 will not be the average size, though, that is very true and selection is limited. I wear size 10-12 and find it irritating when the TV/media makes a big deal about how fat some movie star has gotten (in general, or for a role like Renee Zellweger) and it turns out they are only now a size 12 or so.

Some plus-size stores in Paris are:
Laure Sokol at 84 rue Voltaire 75004 and 137 rue de Sevres 75006 (that may be only lingerie, not sure)

Couleurs, 1 rue de Rivoli, 75004

the one I saw on rue Alesia is Rondissimo at 91 bis rue Alesia, 75014

Un Jour Ailleurs is at: 18 ave Gen Leclerc 75014, 126 rue de Rennes 75006 and 92 rue de Rivoli 75001