Each of my characters I parse... we had to do that in our journalism classes... know each of our characters so intimately that if a random person approached them or asked them a question, or did something, we would know instantly what our character's reaction would be without having to mull it over.
Whether my story characters or my video game characters, each was an individual, unique, special. I did gift each one with some aspect of myself, but not all of my aspects. So yes, the voices and conversations with them, I definitely understand.
I'd be inclined to say look into the PTSD possibilities as well. Just based on people I've worked with and with my own personal experiences with PTSD recently. And definitely keep writing whenever you can.