I would get some D rings (or soldered O rings), make a tube from your fabric and get some nylon webbing. You have an option with the webbing for the handle, you can put it inside the tube, or just lay the fabric on one side and top stitch. I personally would make the tab that holds the D ring to the purse extend a ways down the side gussets for strength. If your machine can handle the bulk, I would also put webbing or some other reinforcement in the tabs. You don't want your PC to drop so make sure that you err on the side of strength for the handles. Hope some of this makes sense. Your bag is beautiful so far!!!!