645 after one month is a strong base, and the percentile split already tells you where the next points are hiding. Quant and DI sit around 75-76th while verbal is up at 93rd, so that's your gap.
On the
error log question, I'd keep one log, not two. The whole point is pattern recognition across your mistakes, and splitting it by source just makes it harder to notice you're missing the same type of question no matter where it came from. Mine was just plain English, a line on why I picked the wrong answer and what I should have caught, and it mattered more than any course material did.
For sequencing, keep TTP as your main track since it's clearly working, and layer OG questions on top as timed practice, ideally in blocks that mimic real section length instead of one-off questions. The GMAT isn't testing whether you can do math, it's testing whether you can figure out what math to do, and OG under time pressure builds that instinct. You're in a good spot, keep leaning into quant and DI.