Hey, I'm glad you are being calm about this and that your mother is being supportive. You should ask her why she's blaming herself, though. It's nothing to do with bad parenthood on her part or irresponsibility on your part. Neither of you did anything wrong; it just happened, life throws us curveballs sometimes.
I'm glad you have a bit of a plan for now. You know you want to work, but maybe when you're child's a bit older, like in five or six years, you can return to school and get a license to teach or something... you did say you love working with children!
I want to wish you the best of luck. We'll be here for you throughout your whole pregnancy if you want support or have any questions!