Pinwheel go round and round

Okay- the sleeves are now in the jacket. Since I am of a more generous size, let's just say, I added more rows before the armholes. I just went round and round until I had 35 stitches between increases and crossed my fingers it would be right. You see, the thing is, when I measure from arm hole to armhole across my back, I get a very similar measurement to the pattern. However, if I measure from the centre of my back to the centre of my chest, I need more fabric. So- I counted on say, 4 inches of ease across the back, the armholes will be correspondingly bigger, and then I need to add the same amount on the front. I suppose I could add even more on the front-but it will also be longer (as the piece is actually a full circle). The provisional cast on is slick and easy (once one can visualize it), and the fabric lays flat (not wavy)
. The picture shows the armhole as it sits now.