I'm going to recommend Sandy Isaacson in Chicago. Sandy doesn't do Pro Bono work as far as I know, but he might be able to work with you over time. I've personally worked with Sandy and his years of experience in the Daily Center give him an edge over a lot of other attorney's in Chicago that charge a lot more!
Here's his link:
I hope this helps!
You might want to check out Illinoislegalaid.org. In their search box type "divorce". Illinois Legal Aid has a lot of information for people who cannot afford a lawyer. After reading it, you might decide to do the divorce yourself without a lawyer!