The number of gears is less important than the high-to-low gear range.

If the 2x8 setup gives you an adequate low gear for the riding you do, and the top end is high enough to keep you from spinning out, then you're fine.

The "more gears are better" crowd will tell you that having just that right gear combination for the current condition is important, but that's a Goldilocks argument. Humans are not that delicate.