coltrane, you could have done many problems but did you REALLY analyze the problems and know why you got each one right AND wrong? It will be difficult for us to help you any further if you do not tell us more about your study approach and progress up until now.
As a first step, did you ever take any practice test like the Kaplan
CD diagnostic? To learn the basics, I would recommend to start with PR math
workbook and then move on to Kaplan800
book. OG is good only for the last 100 DS questions which may be overly difficult though. The math forums on this site have a wealth of resource and will help you with the fundamentals. Maybe you should go through the category based forum and start with the "basic" forum first and slowly progress towards the "intermediate" and then "advanced" categories.
I would suggest you postpone your exam if you can. There is just no point in doing something you're not ready to do. I will give you this link which may help you as a guideline: http://www.gmatclub.com/phpbb/viewtopic.php?t=11176