You’re doing the wise thing to wait and enjoy your low rate over the next 3 years. I’m a mortgage broker and get asked this same questions every week. Unless you have some other reason to refi (need cash etc.) stay put with the lower rate. I tell people in your situation to perform watchful waiting. Keep an eye on the economy and interest rates looking for rate drops.
While most people in your situation worry that rates will continue to rise to their rate caps in the next few years, I highly doubt it. Rates are just as likely to flatten over the next 3 years and even drop again due to recession or global events.
