Looks you have a great list. If your ultimate assignment is going to be to write about the novel in light of these themes, look to see which go together logically. In simple terms you have the theme of love, the theme of struggle, the theme of "family" and the theme of faith. You could can certainly say a lot about all of these topics with this great book.
3. We can grow through painful experiences.
4. We can have many mothers.
5. There is comfort in hard work.
6. Secrets can harm us.
7. Belief in a higher power can help us.
8. Worshiping a higher power in our own image is important.
9. Sometimes we have to fight for our freedom.
10. Love has the power to heal people.
This is one of my favorite books!