Hi Manny,
When you take your future practice CATs, it's important to make each of them 'match up' with Test Day in as many ways as you can (including taking the FULL CAT - with the Essay and IR sections). By skipping the Essay and IR sections on these prior CATs, you took shorter Tests that required less work of you - so those score results are likely 'inflated' and your current ability level is probably in the low-to-mid-500s. The good news is that your score goal is reasonable and you have given yourself a good 'chunk' of study time.
Since you have some study materials already, you should continue to study as you choose for the next 2 weeks, then take a new FULL-LENGTH CAT. Once you have that score result, you should post back here - it will help to define how well your studies are going and what adjustments might need to be made.
GMAT assassins aren't born, they're made,
Rich