I don't have a definitive answer to your problem, but I can relay some techniques that have worked for me to overcome dough which is hard to stretch.
1. Use the dough calculator on this site to get your hydration up to 60%. See how that works for you. The doughs that I have produced at that hydration and using a levain (you use a natural one, I use a starter), are effortless to hand shape into a disc - no rolling pin ever needed. The dough is hard to get used to handling, but makes for a much better product. In fact, doughs produced like this, in my kitchen at least, do not double in size. They merely puff slightly and spread during proofing.
2. If my flour was two years old I would buy a new bag. I just bought a 55lb bag of Caputo Pizzeria. As an example of shelf life, it was produced in January 2010 and the expiration date is November 2010.
What is the technique to increase hydration in your dough?
My dough is roughly 50% hydrated.
If I had added any more water, then the dough would have become un-workable.
Is there a technique to over-come this problem?