Advice about applying to University

I'm pretty sure I want to get into University, only i'm not sure my marks will cut it. I moved from a country that used the British system in their schools, which needed much less self-motivation than the school i'm in, the school gave us work and we did it. I moved to Ontario, Canada in grade 9 and slacked off until the beginning of this year. In Canada only the grade 12 marks count towards the University applications and i'm not doing so well. This doesn't seem to be a common problem on reddit, but i really need help. One option I am open to is taking another year of high school, which is called a victory lap and is common.