As to whether to graduate early or not, it does depend on whether you feel that there is more high school level material for you to learn (i.e. will you have completed the 12th grade or higher level in all of the major high school subjects?), and if you feel that you are ready to move on to college (including non-academically, particularly if you attend a school that would require you to move there, as opposed to commuting from your parents’ house).