Thats neat ... and good for you for taking such great care of the pup. I once had a Great Dane live to 14 - passed peacefully in his sleep, while still possessed of his dignity. Though he couldn't do stairs anymore, and he was pretty much deaf and blind, he could eat and take care of his necessary functions well enough. That was over 20 years ago, and not a day goes by I don't think of him. One of my current pups is an 11-year-old Rottweiler, a very sturdy, stocky, hefty beast, who is still quire active and energetic; he in fact is the alpha dog in our pack (well, I'm the alpha dog, really, but he's my deputy, and all the rest know it). He sleeps more than he used too, and doesn't play as long and hard as he once did, but I can say pretty much the same about myself
The "projected life spans" are nothing but guides - medians. Some pups will not get that far, others will go well beyond. Good care of course is important, but even with the best of care, it isn't up to you how long the pup will live. We recently had the sad occasion to come to grips with the necessity of putting down one of ours (it happens from time to time) ... a 9-or-10-year old spaniel who developed and rapidly succumbed to a quick-spreading cancer. We miss her, yeah, but we celebrate her too. She was a good pup and gave us a lot; we thank her and remember her for that. I think thats all anyone, pup or human, can ask for.