First of all, you still have one month, so cheer up! You still have plenty of chance to improve.
Second, if you feel that GWD is much tougher than OG, you may want to calm down and ask yourself: what is the problem? You mentioned that the GWD problems seem longer, and sometimes you get lost while reading them. If so, is there any way you can improve your understanding and speed while you read? On this board, some people suggested the so called "active reading": http://forum.chasedream.com/dispbbs.asp?boardID=34&ID=2923. It might help. CR passages might be convoluted, but they usually follow similar patterns, so with more exercises you'll crack it!