You say she can't have kids, fair enough I understand, my sister can't have anymore either it will kill her.

But my sister is open to surrogacy, as she wants another child, even though she can't physically carry one.

So that's why I said your gf doesn't want anymore kids, because she's not even considering other avenues of having another child.

And that's perfectly ok too. I only have one child and don't want anymore. The stars would have to be aligned perfectly for me to even just consider having another baby. Lucky for me my bf knows and accepts this.