Forget the appraisal for a moment. A bedroom is a room with a door, a closet, and egress (a window) That is the real estate definition of a bedroom.
When you bought the home did you see it before you bought it or did you buy it sight unseen? Since having bought it have you made any physical changes to any of the rooms removing a door, closet or window(s)?
There's really no way to confuse whether a property has two bedrrom or three and if you made no changes I'm at a loss to understand your question. As to whether you have a chance in court, I strongly doubt it, but that's what courts are for. Who would you intend to sue?
It sounds to me as if you never saw the property you bought and went solely on the word of others, if this is true then it was your first mistake and hopefully you will have learned a valuable lesson, don't buy property you haven't seen and inspected for yourself. If you renovated and modified the home and in so doing lost a bedroom, then again you've learned a lesson.
You may want to give a little more information so that others might be able to advise you more effectively.