Hello Edward,
You many have errors in your form. If you g to file > Designer checker do you receive any errors? It sounds like you may be trying to publish a library form to a list, in which case you cannot do. When designing InfoPath forms list forms and library forms have 2 different XSN types. Here are your options:
1. Create a new Form Library
Since it sounds like your form has been developed to a certain point, you can simply publish to the site and create the Form library. To do so, go to File > Publish > To a SharePoint Server and walk through the publishing wizard. You'll need your SharePoint site URL with just the site and site collection if you're not at the top level.
2. Customize a List form
In this option you can create your SharePoint list, and then from the list tab in the ribbon select "Customize in InfoPath". This option is limited to the columns in SharePoint, and does not support repeating data structures.
If you are not sure, attach your form here and I'll take a look.
Hope that helps!
Bre