Hey Faith!
Based on LibriVox policy, unpublished or self-published works are not accepted unfortunately (https://wiki.librivox.org/index.php?title=Copyright_and_Public_Domain, see under "Additional Copyright FAQs" and "May I record an unpublished work?").
However, all LibriVox audiobooks are stored on Internet Archive. You could still upload your own work to the Internet in the public domain by making an account with the Internet Archive and uploading your audiobook there. The audiobook would not be part of the LibriVox collection or on LibriVox's website, but the audiobook would still be stored and made available online. If you want instructions on how to make an account and upload personally to the Internet Archive, you can send me a PM.
Hopefully this helps!
Elsie