Being stuck.

At the moment, i've been feeling kind of stuck.
I've just recently moved back to Australia, having lived overseas for 9 years. Exactly half of my life. I'm back because it was the logical step after having finished high school to go to university in Australia. This never bothered me, I actually looked forward to it, because since I moved I have felt less and less of a 'bond' with Australia, as weird as that sounds. I just don't feel very Australian, since I had no clue of what was going on there, what was popular or could even understand the new lingo. So like I said, I was excited to re-create that sense of belonging. I wanted to be a typical teenage aussie; learn to drive, get a job, all these normal things I haven't been able to do because of living overseas.
Now that i've been living here for just over two months, I've started these new experiences. And it's great, especially learning how to drive, I can't wait for my license.
However, since it's just me and my twin sister living with our grandparents, we've encountered a lot of free time. The school year is different in Australia than other places, because of summer being in December and all, but this means that anyone our own age is still in school. So even if we did have friends (which we don't really, since we left when we we're 9) we can hardly see them.
And this is why i've been feeling stuck.
Everyday is just melding into one, there isn't really any difference between one day and the next. There's only so much internet/youtube/movies/tvshows you can take before you start feeling stir crazy.  Sure, at the beginning we could fill our days with getting settled, getting a credit card, sorting out medicare, applying for Centrelink (living on the dole basically), looking for a job, organising our room. But now, it just feels like we're watching the time pass, instead of using it.
So basically, what can i do to make myself useful again?