I want to copyright songs that my I wrote before my band started playing them (Illinois)

Throwaway.

I wrote two songs over a year ago. I played one of them live as a solo artist and recorded the other as a demo. I pitched them to the band within the last six months and now they have been recorded and are being mixed currently. How do I go about retaining the rights to these songs? I just have demo recordings and the US copyright office seems to suggest that I would have had to publish them before in order to copyright them.

I am currently under contract with the band and it says that "any and all copyrights in or associated with the master recordings, the recording, and any singles and albums so created shall be the sole and exclusive property of the company." In this case, the company being our manager. I'm hoping to retain the rights to the songs for myself, while still allowing the band to play and record them.