The other side argues that the unborn child has rights and that the 14th amendment does not protect abortion.
You’re trying to tie abortion to ‘bodily autonomy’ because you want abortion to be protected by the constitution. That way, states don’t get to decide for themselves.
Abortion would have better protections with its own amendment, but you know how difficult (impossible?) that will be, so it’s imperative that you find a way to tie it to existing amendments.