You really shouldn't have used up all the NBMEs offline - they are not meant to be a learning tool - they are supposed to be a diagnostic tool instead. You're left without a reliable indicator now, unfortunately. Don't despair though. There is still the free 150 questions available from the NBME themselves. The only other recommendation that I have is possibly a qbank like USMLEConsult or the new Kaplan Qbank (after about June 2010 if you haven't subscribed to it during that time) that you haven't touched yet. If you are getting in the >65% range in 8 sequential random timed blocks I'd say you're close to ready - but it has to be 8 blocks in a row and it has to be taken online under exam conditions.
Good luck... let me know what you end up doing and maybe I can guide a little further...
Good luck... let me know what you end up doing and maybe I can guide a little further...
