Just to be clear: I hope you mean that you have created styles that are used to create the TOC, like the built-in heading styles, not that you created TOC styles. There are nine TOC styles built into Word that govern how TOC entries appear. You do not want to be applying numbering to those.

As for using your own custom styles, take a look first at: Why Use Word's Built-In Heading Styles? by Shauna Kelly

See also: TOC Tips and Tricks by Suzanne Barnhill, MVP