Don't expect too much from ''being 18'', it's not all that special.
You're still very young at that age, and even though you'll be an adult statistically, it won't suddenly change you overnight. Heck, I'm almost 20 now, and I feel nearly the same as I did when I was 17(ish).
Let change and progress come as you grow ready for it, and don't let age breath down your neck too much. It might be good to give yourself structure and a plan on how- and when you want to move on out on your own. But it's not recommended that you let age based society regulations dictate on how you move forward with your life.
It might be a cliche, but it's your life. In the end you'll have to deal with your choices. Better take the time and consideration that it requires. But again, it's your life, all this is merely a suggestion, of course. ;3