I had a quick look at your profile. It appears you’re still at school, and you describe yourself as “still getting used to the Catholic way”. Which means you haven’t been Catholic for long by the sound of it. If you come from a quite secular family, then you’re one of a rare minority to make the jump, particularly in Australia which is not very religious as you know.
So the first thing you need to be sure about is that you’re really being called to the priesthood. I’m not trying to discourage you, but young people can be a bit starrry eyed at times. We need priests and if that is what God wants, then well and good. But if it’s just wishful thinking in your own mind, then you need to be careful.
If it is what God wants, then regardless of what your family thinks, He’ll see you through. But you may find it difficult. I assume they already know that you are Catholic and accept that to some extent.
If you were to become a Jesuit, you could probably still study Maths and/or History anyway. And I’d assume priests study other topics than purely religious subjects.
The main thing is that you need to be clear what God wants, not what you want. Easier said than done I can assure you.