Im 13 a girl from HK and i wanna study overseas like Australia and USA.My parents dont allow.What should i do?

Im a secondary student(we call in HK, which is like middle school in other countries) and since I was small, I wanna study overseas due to my ideal place to settle and my dream occupation. I am quite interested in science and i wanna study about medical or psychology (biology and chemistry). As I know that we are having very easy science compared with other countries. If I study somewhere else, I can orally improve my languages and definitely learn much more than i do now. And that helps me with my dreams very much. I wanna work in the Great Barrier reef, with the aquatic creatures. I love photogrpahy and I really, really like life like this, blue ocean, smooth white sand. I am now on concerning about my future and my parents do not understand me at all. They thought i wanted to study overseas, because of my nasty chinese which i havent passed for a single time. But it wasn't the fact. I wanted to talk to them, but i couldn't. And they made jokes with my dream. At the age of 9 or perhaps 10, they joked that they will send me overseas, I really trusted them and later on i found that it was fake and they said i was too naive to believe that. That really tore me apart . And now on everytime i remember this, tears start falling.. I cannot stop, that's too harsh for me. Please, I need some advices:( Please.....