If you are F5 now you should go to study Grade 12 and then go into university.
I suggest that you find a good private school, where local Canadians goes because as an international student you need to pay to study highschool. Since you need to pay why not go to a better school. In North America (Can & US) private schools are better than public schools, they have lower teachers and student ratio and students will be able to get better care.
As for university, you don't have to choose from Toronto as there are other more famous universities near Toronto, for example McMaster University which is in Hamilton just 1.5hrs away from Toronto and Queens University.