Aimee, my best suggestion right now is to call Canadian Mental Health. You have an office in your city, and even if you don't have mental health issues, they can at least refer you to agencies that can help you. They are the ones who helped me with everything from getting my apartment to accessing AISH (Alberta's disability benefits program for people who can't work for medical reasons) to getting guardianship of my father.
You need to be independent of your mother, because she clearly doesn't seem to give a damn about how her decisions affect you. From my perspective, she does not appear to have your best interests at heart, if she would blow off paying the rent and lie about it, or deny you access to safe transportation.
It seems hopeless at first, but once you tell someone about it, possibilities will open up to you.