Advice on applying to University?

I would suggest that you majorly boost your extracurricular activities because if your grades are not stellar, that's the next thing that universities look at. I don't know about Concordia or Bishop, but it's unlikely that you'll get into McGill with those grades, as the competition is stiff and they even turn straight-A students away. Your grade 10 and 11 marks are the most important because you'll have to submit high school grades in the middle of your grade 12 year so they won't be able to base your admission on your entire grade 12 year. Good luck!