So it’s like the Witcher universe where magic causes sterility in non-elder races? That might be a blessing in disguise; it could have strange effects on the development of the child.
If witches can't give birth, are they like created from human girls through random luck? You get a superpower! And you get a superpower! You bunch over there, all get superpowers!
They are witches, so they can't bear children? Sure. But why would that mean they're forbidden from romance, too?
In the beginning, I was wondering if some of the witches would have yuri developments. But no, unfortunately this seems aggressively straight and heteronormative. Which I suppose is to be expected, in a story that would dress up a teenager like that...