I choose once again to experiment on fabric and I didn't used knit but a rather stiff cotton with very very little stretch. I was a little afraid it will not fit me and it is a good think I traced the largest size in my envelop ( M ). The fit was quite good. I only had to take in a little bit at the shoulders - to wide for me - and the sleeves would have been good to be a little bit larger with my fabric. But I am very well pleased with the shape of the finished product.
I know it doesn't go that well my my big big belly but I still love it and I can't wait to try this pattern again ( and again ... and again ...).