The results are in:

After about an hour of medical speak it all boils down to this:

Carter died from what was most likely a viral blood infection. It did present very much like E.coli but another factor makes it more likely a virus - the liver was not producing the coagulants it usually does - a supposed sign of a virus over the E.coli bacteria. The organ failures were results of that and the hypoxia - not enough oxygen to his brain. It was the low blood pressure that made him ineligible for dialysis and also that low blood pressure that eventually killed him.
Given the inputs we had Dr. Johnston said that Jen and I did exactly what she would have done in our shoes.

Well... now I know how.

In some ways it offers a small amount of closure. The way everything lined up, all the symptoms and the way some were masked, and some external factors - like how our pediatrician acted, I come to the conclusion that God simply called him home. There was no way he was going to come out of it.

It was ordained.

I love you Carter and I take some comfort knowing that God had your days numbered exactly how He wanted them to be. You will always be our little bear. Enjoy your head start buddy! You will have to show me around when I get there!