I am far from the weight police but to answer your question, you are probably over your Truck's Gross Vehicle Weight Rating and Gross Combination Vehicle Weight.
2500 Duramax has these ratings:
GVWR - 9900 LBS.
FRT AXLE - 5200 LBS.
REAR AXLE - 6200 LBS.
Advertised Trailer Max = 17,300 LBS.
These are visible on the inside of your door and stated quite clearly as to what YOUR truck is rated for. Assuming it hasn't changed much since 2011, given the above numbers and your scaled numbers you are already over without loading.
Up to you if you want to worry, you will get varied opinions on many forums. I'm aware that we are close but not losing sleep over it. 98% of our towing is currently in the prairies and the truck handles it like a complete dream. If we choose to head out across the country then I'll review the weights and maybe address it. Others will tell you that you have to have a Peterbilt or a Freightliner to pull that trailer.
But, you did ask