My boyfriend wants a baby

I am 17 and my boyfriend is 20. I am in my first year of nursing school and all he talks about is a baby and proposing. He doesn't have a apt or a car but says if we have a kid he will do what he needs too. He says his grandma doesn't have long to live and he wants her too meet them but im thinking about my life. I just graduated high school and I know a baby is expensive and my mom currently does everything for me with me in college. He is so determined and I keep trying to tell him how hard it'll be and that I don't want to have to struggle and he keeps saying he got it but still. Any advice ?