mrbb, not wanting to sound argumentative but you are incorrect about your support arm not being slightly bent. That is correct and proper form. You will notice, if you watch all the pro shooters, they do indeed keep a slight bend in, if they are right handed, the left arm. With the palm open and the grip supported in the cleft of the palm. This isn't just to eliminate string slap, it is also to prevent torking the bow. I'm by no means a professional archer but I was taught by one of the top archers in the country.

Giffford, do you shoot with a release aid and string loop? If you do, you can adjust some small increments into your draw length by making your loop a bit longer or your release aid, if it is adjustable, a bit longer.