Thoughtful as ever Elle, though I feel you brush aside the power imbalance in this instance and surely the concept of “body autonomy” is not “infinitely more important” than the philosophical issue of personhood (unashamed plug: https://medium.com/@mmacneill123/another-truth-about-late-term-abortion-cabf4fbc4452).
Back to the first point about power imbalance, we are not really arguing about the relationship between, as you put it, “competent adults” but paradoxically, the right of an adult to impose their will on an innocent child. If you reciprocate your argument, it is actually a very powerful defense of infant autonomy.
It is never “just” to do something immoral and we can never have a “right” to do something criminal, though we might assert our autonomy and do something unjust, or we may create bad civil statutes, or engage in immorality and illegality, those bad civil statutes and our immorality do not indemnify us or render us innocent. The idea we can separate law and morality is a peculiar one, forcing its way into legal philosophy in the 19th century— basically because a law is really trying to express a judgment as to what is right and wrong, either for community relations or the country as a whole; justice, by definition, is about the right order of life and is implicitly and explicitly ethical.
Abortion is not a civil rights issue, it is a moral issue and our civil codes should be moral to be just.