Hi emilyweinberg4,
Many GMATers find some aspect of the Exam (the Quant, the Verbal or both) to be challenging, so you're not alone. GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Assuming a similar 'swing' in how your CATs function, your 4 CAT score results show that you essentially performed at a fairly similar level each time, although your 'Score range' is a little wider (530 +/- a few points). You handle certain aspects of the GMAT consistently well, but you also make certain consistent mistakes. The 'swings' in some of your Quant Scaled Scores are likely due to a mix of little mistakes (that you either make or don't make on each Test) and lucky/unlucky guesses (especially on DS questions; here, you have to be thorough about doing enough work to PROVE what the correct answer is). It's worth noting that the GMAT is a remarkably consistent and predictable Test, so you CAN train to score at a higher level.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on your timeline and your goals:
1) How many hours do you typically study each week?
2) On what dates did you take EACH of your CATs/mocks?
3) What is your overall goal score?
4) When are you planning to take the GMAT?
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