Wait! What?
"Who I've been" refers to a few years ago or a few hundred years ago?
IMHO, you are too young to have accumulated so many sins. You have plenty of time to make up for them. And a good percentage of your life you were a kid. I don't think its fair to hold you responsible for things you did wrong when you didn't know better.
I guess it depends somewhat on your religion but I think most of the ones that include reincarnation - our past sins don't follow us. * For instance, I think if you really screw up you come back as a cockroach. But if you do a really good job you come back as a human. So you must have done a lot of good things. to come back as a human. Especially a Canadian. You could have been born in poverty in Syria. or Haiti. If you really do good in this life you get to become one with the universe or god or something. However, my theory is that if you really do good you get to come back as a house cat or maybe a labrador retriever. Anyway, that is what I would hope for.
Fun fact: One of the reasons Pythogarus became vegetarian was because he believed in reincarnation. He was afraid that last night's dinner might have been someone he knew. or worse he could be someone's dinner after he died.
* I am completely unqualified to discuss religions.