?

just now did some research on human's teeth. I still don't understand why I have only 28 teeth :( I checked my teeth out (I could only see my lower jaw) incisors checked, canines checked, premolars checked...er...only 4 molars?! but I couldn't see any possible gap on my  jaw that any 2 more molar teeth can grow...:'( I don't have wisdom teeth? but I could remember that I experienced wisdom teeth pain several years ago...