First, I would not characterize this attempt as a failure. You moved from 595 to 635, and your Verbal improved significantly from V80 to V85. That is real progress.
The main issue is Quant. Your Quant actually slipped slightly from Q81 to Q80, so if your official practice-test Quant scores are consistently higher than that, the key question is why that performance is not transferring to test day.
Also, be careful about trying to judge how well you are doing based on whether the questions seem easy or hard. On the GMAT, that can get into your head very quickly and affect how you handle the rest of the section.
Before deciding whether you need a course, I would figure out exactly what is causing the Quant gap. Look closely at:
1. Your Quant scores on your last several official mba.com practice tests.
2. Your accuracy by question type and difficulty level.
3. Your timing throughout the section, especially whether you are spending too much time on a few questions and then rushing later.
4. Whether your misses are conceptual errors, careless errors, or errors caused by time pressure.
5. Whether you are solving questions in reliable ways that you can reproduce under pressure, rather than using approaches that work when you are relaxed but break down on test day.
If you are already consistently scoring Q85+ on official mocks, for example, I would not immediately assume that you need to relearn all of Quant. You may need much more work on execution, timing, decision-making, and handling test-day pressure.
On the other hand, if your mock Quant scores are also mostly around Q80 to Q82, then there is probably still a meaningful knowledge and skill gap to close, and a structured course could make sense.
With two months, you have plenty of time to make another meaningful jump, but I would make the next eight weeks highly targeted rather than simply doing more questions.
If you post your last 4 to 6 official practice-test scores, including the Q/V/DI section scores, I can give you a much better sense of what I would do next.
Good luck!
- Scott, TTP