Improving My 500-540 Score To a 600+? (Maintain Fresh Study)

Hello Gmatclub, Im an aspiring student trying to further my education and get accepted into a decent business school. I graduated from Fairleigh Dickinson last year with a B.A. in Psychology and I've come along way since I made the decision to begin studying for the GMAT. Considering I don't have a strong background in math (I never took the time to develop the interest) Im proud of the strides I've made, and it is reflection of my growing interest in math and sharpening those skills. I feel I need guidance and have reached sort of a road block so I'll debrief my journey to provide context:

I started at square one with the GMAT 6 months ago, I took my first practice test and did bad naturally (high 400s, low 20th percentiles in both sections and I did the Foundations Of GMAT Math book to refresh everything I had already learned. After that refresher I began working on ALL of the MGMAT strategy guides to sharpen my skills in the areas I needed to on the test. Once I finished I even made a point of going back over the quant books again to really get a hold on everything. After I finished the strategy guide books I started this syllabus that took me chapter by chapter in the strategy guide books and tested me in the OG13. I completed the syllabus, keeping record of my percentages (right/wrong) in each section and error logging my answers for review to really work on my weaknesses. I did the error log by pen in hand. After I finished the syllabus and felt comfortable with the bulk of the material and the overall feel of the exam, I took the Diagnostic Test in the beginning of the OG13. This was my analysis for my performance on the Diagnostic Test:

PS: 14 Correct - 11 Wrong (Silly and minor errors in 6 out of the 11 questions I answered wrong. Those questions were within my grasp to answer correctly. I had a problem with geometry and analyzing the purpose of the questions (what exactly it asked of me). Another weakness here was devising formulas efficiently for word problems

DS: 16 Correct - 7 wrong (Similar weaknesses for me in this section with geometry concepts(coordinates), I also had problems testing the extreme cases necessary for DS problems, and I had problems with sets)

RC: disclaimer - reviewed RC a day before I took Diagnostic. 16 Correct - 1 Wrong (I did good here and im not sure its because I had just finished studying because I didn't maintain this level in subsequent practice tests but I'm pretty comfortable with spotting conclusions, mapping the body of the passages etc.)

CR: 11 Correct - 5 Wrong (There was supposed to be 17 ?'s but I finished one prior to the test. I took longer than 2 mins per question this section and I had issues with spotting the premise and pulling assumptions from premise-conclusion relationships. I also had issue with breaking down question types)

SC 8 Correct - 10 Wrong (Bulk of the problems I got wrong were parallelism, verb tense, and I let multiple modifiers confuse me with the questions. Problems drew me into the words of the sentence while I lost vision of the overall structure of the sentence. I finished in 21 minutes so maybe some of that error is attributed to me going too fast?)

Total Diagnostic ?'s - 66 correct - 34 Wrong (66%)

After I took the Diagnostic Test I began working on practice problems and pacing, which I improved in and I tried to stay accurate by attacking my weaknesses. I then registered for the Economist GMAT's 7 day free trial and did as much of their material I could in 7 days and took their practice test the last day. The results I got (540) from their practice test are attached and I will screenshot more info. At that point I was pleasantly surprised coming from where I was and seeing improvement let me know I could continue to improve! I went from the 400s to a 540!

I also took the mba's practice test last week (albeit not as mentally prepared as I was for the economist's practice test, which I admit complete fault to, I started off slow, my mind wandered atleast once for each section and the RC stomped me). I got a 500 on mba's GMAT and im not sure if its because it is harder than the economist gmat or me not being mentally prepared but I didn't finish a handful of verbal and quant questions on the practice test (around 5 to 7 all together).

The main problem I want to address is keeping the momentum and constantly improving but I do feel my studying route after the economist practice test has gone stale! From start to finish I "learned - practiced - syllabus & practice - diagnostic test - practice - economist test (high point) - practice" Now it seems my study is reduced to just practice out of the OG13, Quant and Verbal Review books with taking more practice tests. Im not sure if its the right route but I want the improvement to continue.

I would LOVE to get in the low 600s from that 540(but I do want to max out)!I know that the 540 on the economist test wasn't my ceiling and I can do better, I just need a better plan moving forward, assessing my weaknesses and working on them because from the time I took the economist practice test to mbas practice test there was a -40 in my overall score(even though I didn't go into it as prepared as I did for economists test). I plan on taking the GMAT January 7th but im flexible if I deem it necessary to improve my score.

I would DEFINITELY appreciate ANY and ALL tips, advice, studying methods and guidance you have for me to continue improving and even study better than I've been studying! Please give me a hand, I can take criticism as well as advice and I'm willing to do what it takes! I know I've posted a lot of info but you're time is very much appreciated and my economist test scores are attached! THANK YOU!