We can argue that today, in a world of limited resources, there is an obligation for everyone to practice population control. A more common explanation of this halakhah is that we should reduce our pleasure when other people are suffering. Perhaps today, with so much poverty in the world, we should deny ourselves the pleasure of having children, especially because this self-denial would help to reduce population growth. Adoption is highly praised in Jewish tradition, and according to some teachings it fulfills the mitzvah of reproduction. On the other hand, although there have always been orphans and unwanted children, Judaism has never said that anyone is obliged to adopt, even a couple without children.
Adoption is hard.
Today, adoptive parents go through long delays and huge expenses in order to raise children who often come to them with physical or emotional problems. We have to do acts of kindness, but which ones we do, and how much, is up to us. So for every issue in your question, there are good Jewish arguments on both sides. I invite you to think through the arguments and draw your own conclusions. Although you may be stricter with yourself, there is certainly room within Jewish tradition for her to have a child.