I feel in a similar position - have sat the GMAT twice in the last 6 months and went from 530 to 590.
I can get a decent score on verbal without breaking a sweat or spending any time studying it (usually V41, 93%), but i'm having to build up the quant skills from scratch (still only scoring around Q31; 33%).
Finished going through OG12 - each question timed and understanding the answers. Then went through all the questions I got wrong again.
Was booked in for a test tomorrow (24th April), but just scored 600 on GMATprep1 (Q32, V41) so am not going to bother. I need the next score to come it at 660 ish to justify the re-sits and show progression. Have another exam booked for 29th May, so it's 1 month to go until they change the exam structure - for me it's last chance saloon.
The main thing i've found is that the actual GMAT quant questions are quite different to those in the OG. I guess the OG starts at a basic level to make it accessible. Anyway, I'm going to purchase the
MGMAT "Quantitative Prep Set" and work through that. You also get 6 test exams, which are supposed to be at a tricky level. My theory is that if I can get my head around the
MGMAT q's, I will not look at the actual GMAT ones and panic, which is basically what happens now.
For verbal, I'm pretty sure I could crank it up to 99%th if I have time to work out which q's i'm slipping up on.
I think confidence is everything with this exam - I look at the verbal, enjoying reading through the questions and really don't stress about whether the answer is definitely right (because I know i'm probably going to be ok). Whereas on quant i'm staring down a 1000ft pitch black mine shaft!
Don't know if any of that helps / resonates... Also interested to hear any more experienced views.
H