I diagree with this because I couldn't wait to get out on my own and I had and still have a good relationsip with my father and that was 25 years ago. Every ones situation is diffrent. I would however, always plan for the worst case scenario.

Fastest way to get out on your own would be to join one of the branches of the military. This option usually pay ot a decent bonus and pays for school. You could join a active component or guard/reserve for part time but you will likely deploy somewhere before the term ends. Second would be try to get a colledge grant or scollership an move into a dorm, finish colledge and get a decent paying job. Like mentioned above don't rely on you gf this could end badly. Coast of living varies per state so google cost of living where you plan to locate to. Life is not easy so start saving now it will help you in the long run.