A 655+ is a credible target from where you are, but I would not treat this as simply a matter of doing more questions. You’ve already shown that you can produce Q82 and DI82 together on an official exam. The next step is making that level more consistent while improving Verbal, which has stayed between V78 and V80 across all three attempts.
For Quant, I’d focus on maintaining the Q82 level and identifying the specific topics or question types behind your remaining misses. I would not rebuild Quant from scratch.
Verbal looks like the clearest opportunity for additional points. I’d concentrate less on trying to improve your English broadly and more on mastering the reasoning the GMAT repeatedly tests. For CR, make sure you can clearly identify the conclusion, evidence, assumptions, and exactly what each question stem is asking. For RC, focus on passage structure, author purpose, and the role of each paragraph rather than trying to remember every detail.
DI is worth investigating carefully because you’ve already scored DI82. The drop to DI75 on your third attempt could reflect a particular question type, pacing, execution, or normal test-to-test variation. I’d review that section closely before deciding what kind of DI practice you need.
Regarding practice material, once you’ve exhausted the OG, I would not start doing random DI questions from across the internet simply because they are new. Quality matters enormously with DI. If you’re using TTP, the DI problem banks, chapter tests, Custom Tests, and Reinforcement Tests can give you a substantial amount of additional practice.
You can also revisit official questions after enough time has passed, but I’d use them primarily for analysis and process, not as a clean measure of your current ability. Ask yourself: What is this testing? What clues should have led me to the right approach? What is the fastest reliable solution? Why are the wrong answers wrong?
With 2 to 3 months, I’d spend most of the next several weeks on targeted Verbal and DI work, keep Quant sharp, and use fresh official mocks periodically to see whether the improvements are translating. I would not burn through mocks every few days.
Most importantly, don’t let the 575 convince you that you’ve gone backward. You’ve already scored 615 with Q82 and DI82. The job now is to make that level more repeatable and raise Verbal enough to close the remaining gap to 655+.