I have sensitive content blocked so I get a warning and I can't see your game. Based on your description I would not want to play your game either (I'm overly-sensitive to violence). So for me, the warning is useful and I appreciate it. But generally, I encounter violent and horror games all the time without them being flagged.
The flashing lights is not an age-related thing, that is dangerous to some people, so that's a nice warning to have.
I think if your game has elements in that aren't suitable to younger audiences, then you're doing the right thing by having the 18+ warning.