I'm actually not sure if anything else happened when I was a kid but I tend to block out events and o...
I'm sorry to hear all that happened to you, but glad to know your dog survived.
I don't think you're over-thinking... it is something that has affected you, something that traumatized you. I think at 12 yrs old, children pretty much think in an insulated way, ie dont think about consequences, mortality, etc. So to come home to that would be frightening, for sure. The home invasion, like you said, worse. That had to be horrible.
I would imagine if you were taken to a Dr after that incident and the Dr was basically told you'd been acting diff since that time, he/she would diagnose (which they shldnt, but..) based on that. I still can't see adhd and bipolarity coming from that one incident.
Did you talk to a therapist back then? Do you now?
Misdiagnosis are common, to be sure. Just looking at symptoms of PTSD and say, anxiety or depression, borderline personality disorder, etc, they have similar symptoms. It sucks that at 12 the Dr didn't take more time or suggest a therapist, especially with the meds he probably prescribed for you. Long term, I would think those type of meds shld come from a psychiatrist...
Anyhow, maybe the incident at 12 triggered something from when you were younger? Idk. It probably would help to talk to a therapist whatever the case may be because it clearly bothers you still, and understandably so.
Take care and hope this helped a bit...