Status update: I cut out my bodice pieces in the striped silk and managed to match them in a chevron pattern around the bodice. I didn't need to baste anything, which I was expecting to do, because the silk wasn't actually that slippery. I've found that if you really want to match stripes on slippery silk you have to hand baste everything and put a stitch in every point that needs especial matching.!
I changed the shape of the sleeve to almost square so I could fit it on the fabric. An old solution to not enough fabric was to "piece" the fabric, which means cobbling together several pieces into the shape of one. If you had a one piece sleeve you could match the pattern of the fabric together and puzzle piece it, basically. I've done it a few times on historical clothing, and it works surprisingly well.
On this project I only did piecing on the skinny ribbon pieces that are decorating the skirt. It is difficult for me to see the seams, even though I sewed them! Strong patterns are easiest to piece because your eye is already distracted by the pattern. 
Can you see the pockets? They're satisfyingly invisible.
I raised the armscye (the curve under the arm) twice, since the first draft was too low. Since I'm not using measurements to make a flat pattern and I really only kind of know what I'm doing I get silly things like that wrong. I'm still a little worried about how low the armscye is, and hope that it works. It should, since I field tested it in sheet, but if I'm wrong I'll have to piece it. Maybe I can make it look like I added gussets under the arms.
Here are the pockets!