Hi All,
The point that dontquixote is trying to make is a good one: using just pencil-and-paper resources during your studies can be problematic. Even with the occasional CAT, you're not training yourself to work in the proper format, so your results might not be great.
Using some of the additional details that were provided, here are some other things to consider:
1) Studying for the GMAT takes time. You can't really "cram" for it, not in the way that you might have crammed for a College/University exam. So 2 weeks of study time isn't likely to be enough to lead to any big improvements in your score. A longer overall period of study will likely be required.
2) There's a lot more to prepare for than just the content. You might know your math formulas/rules perfectly, but you still have to perform at a high level, across a variety of subjects, for 75 straight minutes. You also have to manage proper pacing and deal with the common fatigue/endurance issues that everyone faces on Test Day.
3) You MUST finish ALL of the questions in each section. If you run out of time, any question that you do not answer is marked 'incorrect' AND then penalized. It's better to guess on those questions at the end then leave them blank.
Thankfully, all of these issues (and many others) can be trained for. The GMAT is a predictable, standardized Test, which means that you can learn the content, patterns and secrets to it. You'll likely need to invest in the right resources, and you'll certainly have to work hard, but the process is not a mystery. Others have scored at a high level on this Test and so can you.
GMAT assassins aren't born, they're made,
Rich