GMAT Strategy

Hi all,

I am posting this question after getting tired of looking at the same results of every mock test. The funny thing is that the quant score in my diagnostic test, that I took 4-5 months before, is exactly the same as on the most recent test, even after studying so diligently.

I have used up all my resources of GMAT. I have read and solved each and every question of MGMAT guides, OG and various other sources. It is not that I didn't time each problem. I did time all problems and could manage to finish most of them under the prescribed time limit ( I maintained an error log as well).

After carefully perusing and scrutinizing my assessment reports I resolved that probably I am not able to increase my score because I have not been using right strategies such as plugging in and back solving. But when I sit and take the test, these things just don't strike me at the right time and to add over, I get anxious and end up marking randomly.
I get only very hard and around 70 percent of hard questions wrong, so I believe that I have a grip on my fundamentals, or could I be wrong?

How should I actually apply these strategies on the test? How can I get very hard and hard questions right?

In dire need of help - I have to take GMAT in 10 days.

PS- I always thought I am bad at maths, but throughout these months of GMAT prep I realized that it was untrue. Now after not being able to increase my score, I am again tending to give credence to the fact that perhaps I am not good at maths.

Regards
Sukriti