Making my first quilt...How do I prevent batting from getting "bunchy" or bubbly?

make your silk part a duvet cover by adding snaps or ons to the opening. buy some lightweight inexpensive fabric to quilt your batting inside of. This goes inside of the silk part like a pillow. put ons or snaps on the inside seams of the silk part and align on holes or snaps to the quilted batting part so the quilted part doesn't slide around inside the silk.