Just packing the essentials? Go for the Andi Small bag. Wear it as a crossbody with the detachable strap. One outside pocket and three on the inside, you'll stay nice and organized. And just to be extra, it comes with a small removable pouch. 

17” x 10” x 4” compacts to 7” x 3” x 2”

Fabric:

100% nylon