Would a septoplasty help alleviate headaches, pressure, and chronic sinusitis?

The first thing that I would recommend is that you see an ENT doctor who specializes in sinus issues known as a rhinologist. That physician will spend time to determine whether or not you have sinusitis and whether or not it's truly chronic. There's a lot more to know before one could answer your concerns and guide you better.
Having performed septoplasties regularly for more than a decade, I can tell you that it can certainly help with breathing if it is deviated. I have also had patients have improvement in the number of sinus infections and, less commonly, improvement with facial pain issues. That being said, I've had many who had no improvement with these other concerns outside of breathing.

Hi there! It's likely that breathing improvements will occur after surgery if your septum is severely deviated. As for sinusitis, it can depend. Sometimes, improved airflow does reduce symptoms. Other times, it's a distinct process. I would recommend a CT Sinus to evaluate if there's any disease located within your sinuses. If so, that may require a different form of treatment. Hope this helps!