I don't think I've posted to you before, but I lurk occasionally. I just wanted to send a big cyberhug your way, and how sorry I am for the loss of your baby. One thing that struck me is your wondering if you could have "done" something to prevent it - I'm in the medical field, and the stats are that 60% of all conceptions, or potentials pregnancies, are lost; and that one woman in four will experience an early miscarriage at some point. It is extremely common. That doesn't make it any easier to bear the hurt, but it is certainly not your fault in any way whatsoever.
Take care of yourself and your son. You deserve it.