CMV: "my body my choice" makes no sense

FYI this is a thought experiment in logical consistency. My actual stance is super nuanced and not as it may appear....

I don't get why people claim "my body, my choice", as a retort against anti-abortionists. It's not about your body, it's about the life of a child. Why would your right to bodily autonomy supercede a child's right to survive? The law protects our lives, murder is a crime. It seems like the only logically coherent pro-abortion quote should be "a fetus aint one of us yet", but I guess that's just less catchy?

Related... At what point do you consider a fetus "human enough", to be worthy of legal protections like the rest of society?