You can try an Eddie Bauer First Ascent Downlight Sweater. They have XS, short, regular, tall.
Unfortunately, the screaming $42 last year's model sell-off extravaganza is over, but they likely will have another sale after Christmas. The new model (at least in men's)is suppose to be a tad heavier but more downproof.
I got an XS for a friend, it fits her to a T and looks pretty nice in red. She's like 5'2-3, medium build. Lots of First Ascent stores though, so you can try it on.
Supposedly the EB is comparable to the Alpine Light in warmth. However, not sure these jackets (4oz of down) will keep you warm down to 15 degrees inactive though. I was pretty warm standing around fishing in mine with a baselayer down to -2*C. Might have been able to pull 15*F/-10*C off with my rain-jacket.
Maybe a Westcomb Kokanee. Might find one on sale. Montbell sold in Japan is smaller.
The more stitches the greater chance of cold spots. Baffled construction is better but more expensive.
Not sure about the less down because of less fabric. There's a slight discrepancy between final weight and men's sizes, but I attribute that to material, not down, weight.