I like the wool for how it drapes and how it feels. It's not hot in the summer and it the perfect amount of hot in the winter. It kind of self regulates. You can get Dream Wool in a pretty thin batt too.
I hope you pre-washed your cotton fabric. The silk won't shrink but the cotton will. Same with the batting.
With such a special quilt made of something so special as your dress... I would soak the batting in as hot a water as you can fill your tub with first. Let it soak till the water cools down and make sure you've pushed it under the water to make sure it got really good and wet. Then, open the drain and just let the water drain out of the tub for a while, even overnight.
You don't want to put the batting in the washing machine and have it swirl around in water with the machine as the wool will felt and become a big mess. But, after the water stops flowing out of the batting (I usually just leave the tub draw open overnight), I do stick the damp batting into the washer on spin cycle only and use the spin cycle to get as much of the rest of the water out as I can. Then I lay it on the floor with a fan and let it dry, again it usually takes over night.
This might seam like a real pain in the butt, but unless you can get your hands on some Matilida's wool batting (out of Australia), all U.S. wool batting will shrink some, and it will shrink at a different amount than the cotton quilting fabric.