@watk,
Consider accepting that this is not a perfect world, and things aren't always the way we want them to be.
At 16 years of age, it's hard to imagine any boy being thrilled to be a father. Granted there's always exceptions to the rule, but generally speaking, from western worlds, neither girls, nor especially boys are ready for for parenthood at that age.
Sometimes the idea of something (in this case being a father / raising a child) catches people by surprise, and they aren't sure how they truly feel about something, so at times it takes a while to get used to something new, and other times things just grow on you. That may or may not be the case for you and your boyfriend - it's one of the complications faced by unplanned and early life pregnancies.
I don't have kids - aren't there pre-natal classes (or something like that - that questions aimed at others) that you can do together, and see how things go?