@Jennessa *******
nope the Non-B visa lets you get a work permit, the work permit lets you work here, the extension is what you get AFTER your Non-B visa's 90 days runs out and that's what lets you STAY here
AND
As I said you need to cancel that extension at the immigration office where it was issued with documentation from your employer BEFORE you exit the country. 🙂
So if you've been in the country longer than 90 days you're NOT on any Non-B anything, you're on an extension of stay (which is issued a year at a time usually)