Avoiding getting Pregnant

I been with my bf for three months and  we haven't been  using condoms or any kind of protection now Im just scare if I did get pregnant , he's older then I am but I just feel that Im to young to have kids at age 20 want to know I can do to protect myself with out using birth control since people tell me it dries you womb to have children later in life and I want some but when I'm older and stable with my lufe