Hi jain808,
The scoring algorithm on the Official GMAT is far more complicated than most people realize - and it takes into account more than just the number of correct answers. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. The most realistic CATs available are the 6 from GMAC, but the CATs from Kaplan,
MGMAT and Veritas are all 'close enough' to the real thing that they will provide you with a relatively realistic score assessment (assuming that you correctly take the CAT in a realistic fashion that matches the parameters that you will face when you take the Official GMAT). For your next CAT, you should plan to use a Test from one of those sources.
As far as RC is concerned, to perform at a high level, you do not need to understand everything that you read and you do not need to be a 'fast' reader, but you do have to approach each prompt in an 'active' fashion and take appropriate notes as you read.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied for this 2nd attempt? How many hours do you typically study each week?
2) Have you used any other study materials besides the books that you mentioned?
3) On what dates (or approximate dates) did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich