I know everyone's journey is different when preparing for the GMAT, but 4 months is a long time to focus on just the Quant section.
Without much research, I joined
Target Test Prep or TTP. I made my study plan and was shocked that I would need minimum 180 hours just for Quant. That was a huge leap from the 150 hours I thought I would need to prepare for the entire GMAT, not just one section. Following their plan, I felt like I was never ready to take the GMAT and needed to keep working on the modules. More months, more money for them. Frustrated, I reached out to friends and coworkers who had already completed their MBA, and I was told I may have wasted my time on their material.
I NOW know I should have researched more, especially on GMATClub (great info), what online Quant prep course was best for me. Not just repetitive learning, but learn what the test makers are asking. Quant question seem weird at first, but once you understand what they are asking, the logic of it starts to click.
Good luck on the test! I have no doubt that after 4 months on one section, you're bound to be Quant expert.

However, those without that much free time, like myself with work, life, and family, may want to look into courses that teach you what the GMAT test authors are looking for. I'm still researching what will be best for my learning, but I know TTP's 180 hours Quant study plan is not it.