The bag in the listing you've posted is authentic. And although your bag may match exactly and have a valid serial number, we need to see pictures of your bag in order to authenticate it.
Counterfeiters can and do put valid serial numbers on fakes. It's the details of the bag that determine authenticity and not the fact that it has a "correct" serial number for the style.
If you can either upload pictures to a post or upload them to photobucket (or another photo-hosting site) and post the IMG links, we can give opinions on your bag.
I do have a couple of other comments.
1. Existence or non-existence of a YKK zipper has nothing to do with authenticity. Coach uses YKK as well as several other brands. And the fakers use real and fake YKK.
2. Calling Coach is almost useless as a way to get correct information about bags, styles, authenticity. The bag in the lisitng was made in 2003 and if authentic, your bag was from 2001. Chances are that the person you spoke to on the phone was in diapers in both of those years and probably hasn't ever seen a bag that old!
Once you're able to post pictures of your bag, it can be authenticated.