Back support is not limited to the date you filed the petition; under certain circumstances you can obtain support retroactive to date of birth, plus birthing expenses, etc. You would have to prove a few things, such as that he had knowledge of the minor's birth, made no contribution or less than statutory guidelines, etc.
Contact your states attorney's office, who may be able to represent you in the support issues. The rest of the issues will require you to file pro se, or retain an attorney.
He doesn't owe any back child support because in Illinois it's backdated only to the date of petition. He's not "legally" the father, not does he have standing to contest an adoption unless he intervenes. Perhaps he is the father, perhaps he's not. Who knows. What I do know is that your problem, until he gets involved, is pretty simple to solve.
Contact the Moultrie County Bar Association for assistance.