I don't necessarily agree with you on that point. My mother had my sister at 18.... And a vast majority of her friends had kids young.... Their kids are happy and well loved.
Don't compare what you feel your mother has made you feel, to how good or bad of a mother you'll be.... You are not your mother!
It doesn't have to be that way.
My husband just turned 17 when we found out we were expecting.
It's very scary, and i'm sure you feel overwhelmed. Take time to look deep inside and find out what you really want to do....It's up to you!
As I said before.. We're here for you :)