So I bought two books on my Nook and i know for a fact they both have over 300 pages but it says at the bottom when i scroll through that there is only 189 why would that be did i get ripped off?

You may not have been ripped off but you may have a bad or incomplete download. Call 1-800-THE-BOOK and talk with customer service. They may be able to confer it's a bad download & get a refund.