What helped me a lot was a simple and obvious thing: write everything down, even though it is very simple.
The reason is as follows: Your brain has a limited working memory. There is only so much you can visualize or so much information you can keep on top of your head when approaching a difficult problem. If you write things down, you will be able to free up some memory in your brain to upgrade your thoughts/thinking. This is especially important in Data Sufficiency (i.e. testing positive and negative numbers to fit the statement), inequalities and geometry.
In my opinion, going through 1000s of problems is not going to get you there by itself. I cannot explain it to you why, because I am in similar situation like you except that I have considerably more time to figure it out.
Hope you find this information a little bit useful