You'll never know if you don't train. It's possible, even probable, that you can get there with appropriate training - but you have to define your goal. 'Good Vertical' is not a definition. The NFL Combine are superlative athletes, and vertical jump numbers ran from 24.5" to 44.5" this year. You aren't far from the low end, but I'm guessing you aren't a gridiron football lineman.