quant advice

I am taking the GMAT feb 8 of this coming year and I have the MGMAT 8 pack set and so far I think its awesome. I scored a 520 on the test (forgot my quant, but my qual. was 41). Basically I was terrible in math classes in high school, coupled with my lack of interest led to a pretty poor score. Anyway I regularly get 600-700 level quant questions correction in the OG, I have EIGHT WEEKS to devote to studying and NOTHING else. I have worked through 2.5/8 practice books so far. My question is, given my time frame, should I invest in the Jeff Sackmann 1800 question pack, or does this seem like too much given my time frame? I still have 5 MGMAT books to work through, and 7 practice tests...I don't want to overwhelm myself to the point that I do worse. BTG questions seem good too but people seem to swear by Sackmann's materials. Any feedback is greatly appreciated. I should add in I'm applying to schools that require a 550-600 on the test, I understand I'm only 50 points off where I stand right now but 650-700 is a personal goal of mine.