As others have said, wait. You are only 15 and there is plenty of time for you and your boyfriend to think about having a child together.
Are you prepared to wake up every few hours for feedings, changings, or just because you have a fussy baby? Do you really want to think about losing most of your friends? They say they'll be there but when the time comes most of them will turn their backs.
Have you got the house, car, insureance also? What happens if you have a child with mental or physical disabilities would you be able to cope with that? It's not all fun and games. And babies are expensive even if you think you can get all the baby stuff you'll need you still need to provide for that child until they are at least 18 and pay for them to go to college.
Having a baby will put a huge strain on your relationship with your partner. If you want to go out with your boyfriend you have to arrange a baby sitter which isn't that cheap either. Everything will revolve around the baby.
I think you should go to college and get a decent career so that you and your boyfriend can stand on your own two feet without having to rely too much on either set of parents for a place to live, use them to get to medical appointments, financial help etc.
Being only 15, you have plenty of time for kids your biological clock isn't running out yet. And have you considered the physical strain pregnancy will place on your bodies? It's hard for someone in their 20's, 30's or 40's let alone in their teens.
Wait and live life as a teen, you might not think so now but you will be glad you waited when you are older. My mum was a teen mum and I believe that she wishes she had waited even though she loves me and wouldn't change anything. She lost out on a lot of things as a teen and I think she's living that life now in her 40's because she missed it when she was younger.