Wow, you will totally destroy your life if you have a baby at 15 years old. Do yourself a favor and volunteer on the pre-natal floor of a hospital. Get some experience taking care of a baby, or even babysit a baby and see how you deal with the pressure and taking care of a baby. And remember, you need to have money to take care of a baby. Do you and your boyfriend have plans to get a job if you do have a baby?
I really think you need to think this through before you go having unprotected sex with your boyfriend again.