how do I tell him no?

I'm 16 about to turn 17 and my boyfriend is 17 about to turn 18. for the past 6 months, all my boyfriend has been talking about is how much he wants a baby. it's typically the other way around, I know. one of his friends just recently had a baby with his girlfriend, and after seeing them with a baby, it has him convinced that we need one because he's "ready to settle down and be a father." my logic is, if he's ready now, he'll still be ready in another 10 years. I mean, yeah it'd be cool to have a baby now I guess, but we both still have our lives ahead of us. i want to have a baby when I'm financially stable on my own. my boyfriend already has a steady income from his family business and he makes decent money, so I know that we could financially do it if I got a job too (just so that he wouldn't have to pay for everything) but I don't want to end up having to drop out of high school. how will I graduate and then move on to college if I have to take care of a baby? I don't think I could do it. I'm scared that if he keeps asking he'll convince me (because, like I said, I think it'd be cool to be a mom) but I still want to be able to go to college and get an education to be able to support the baby for the rest of its life. I've told him all of my reasons for not wanting to but he always comes up with solutions. I can tell he REALLY wants this and I don't want to disappoint him. any suggestions?