How do I get a copy of my birth certificate?

So I've been wondering if I was adopted for several years now. My parents have always treated me differently from my sister and brother, like I'm some sort of freak. They always used to beat me up and call me names, and whenever they were mad at me, they'd always yell "this was all a big mistake! we never should've brought you home!" and stuff like that. My brother and sister both look like both of my parents. I look nothing like them, except for the fact that we all have black hair and a light complexion, except for my parents because they were born outside of this country. People always tell us that we look nothing alike. They always mistake me as a family friend or something. People are always telling us that we look so different from each other. I've asked my parents if I was adopted several times before, but they've just gotten upset over it and refused to answer, so I don't wanna bring it up again. I want to see my birth certificate, and I've asked to see it, but my mom said that legally they're the only ones that can keep a copy of it. I don't think that's true.. I'm 14 and I really need to see my birth certificate. There are no pictures of me in my mom's stomach, or of the ultrasound. There are no baby pictures of me up til I was 8 months old. But there are several pictures of my older sister when she was a baby.I don't understand.. I live in Canada btw, so is there a way I can get a copy of my birth certificate now, or do I have to wait until I'm 18?