It looks like you're all set if you are a Canadian citizen. However, it would appear you'll need to prove you are one first (maybe that's why the consulate said you can't get a passport). You might want to look up how to get proof of citizenship at www.gc.ca You'll need either your birth certificate (if available) or a certificate of canadian citizenship. Since you were adopted and taken south of the border and live there permanently, it may be easier for you to have the latter for future renewal. It may be a lot of work so better to get going on it.

Here's a review of the process

http://www.ppt.gc.ca/usa/index.aspx?lang=e