Help! Struggling with GMAT preparation

Dear all, I need advices for my GMAT preparation. I plan to take the test in 3 months (by the end of May) and my target score is 750 (or around). I bought the 10 books of Manhattan prep and the 3 books of the OG 2017 I've been studying the quant part for almost a month now using the OG but i felt li...