why am i always thinking about bad things?

i (f19) always, and i mean ALWAYS, am thinking about bad things happening. i think about escape routes from every room im in, plan for if an intruder breaks in, etc. these things are genuinely on my mind in extreme detail almost 24/7.

in addition, i have nightmares every night of extremely bad things happening. this has been in my mind for as long as i can remember, and these thoughts don’t stress me out, so i don’t think it’s anxiety, but im not sure what else it could be. is this normal?

if you have any questions to clarify plz lmk because im sure im not explaining this well lmao