I specialize in auto accidents in Michigan so I am not familiar with NY law. However, I would suggest that you contact your attorney and tell him/her that you are not happy with the services so far and you would like a face to face meeting. The question you posed is very common and should be easy to answer. Just because you visit a doctor every 6 weeks does not give me or anyone else enough information to tell you how much your case is worth. It may be worth nothing or millions depending on the prognosis and diagnosis. Talk to your attorney or get a new one.
Good answer above - your attorney should be able to answer your questions. Just ask the attorney what you should expect to happen the deposition, since the attorney has financial interest in the outcome, I see no reason why they will not want you to be prepared.