should i move to australia or stay in new zealand?

Ok so my dad has moved to Australia and has found a job. So his plan is to work there until the end of the year and so my mum, my little brother and I can join him next year......the problem is I'm already in year 11 and only have two years till i finish high school....so i don't want to leave my stable position....i also heard that the schooling there is not so good? but if we stay two more years my little brother will be in year 11 and so the cycle goes on. i really don't want to hurt my dad, cause he misses us so much but he is still willing to do his best to help us out, and i'm here being really selfish and ruining the whole plan for my whole family.