I won't try to talk you out of steel, but fwiw with carbon you don't feel every bump and crack in the road. Carbon offers a rather smooth ride, which is why they add carbon forks and seatposts to aluminum bikes.

As for sudden failures, that's not really a problem either. The damage is generally caused by an impact like a crash or hitting the frame against something.

Regardless, I don't think being on the short side necessarily means you need a WSD frame. A small version of a non-WSD frame might fit you fine, depending on the frame dimensions and your reach, inseam, etc.