Let's see... Did you talk to the merchant after your buy her? He says to do it when you are ready after you get her contract, and that's when she is brought to your house, together with you. Maybe you forgot to interact with him.
I understand. I made it this way because I didn't want to "warp" players back to Tarkas if they still had stuff to do in Rahib, but perhaps I should make it automatic, or at least change the text color so that it's more noticeable when he tells you what you need to do.
