It's worth noting that antinatalism is by no means an uncontroversial opinion, even granting your three assumptions. For example, argue that despite the consequences to the environment, bodily autonomy outweighs the rights of the not-yet-born. As a loose analogy, consider bodily autonomy arguments for abortion; even if a fetus has a right to life, it doesn't outweigh my right to control my own body. So is it if the 'fetus' is a human who will be born 50 years from now.

So some feminists will be against antinatalist programs simply because they are opposed to antinatalism. If it were necessary to team up with the powerful antinatalist lobby to pass laws supporting girls' education, some feminists would be willing to do so. But since antinatalists aren't, to my knowledge, actually influential at the level of policy it's hard to see why such politicking would be necessary.

Probably, if you want feminists to team up with antinatalists your best bet would be to just try to convince them to be antinatalists themselves. But this is hard, because as I touched on in my first paragraph, some feminist principles lead one to conclude that antinatalism is wrong.