OP, I've never been in your situation, but I can you this much: even when a pregnancy is planned, there are moments of doubt. I don't think anyone is ever 100% ready to have a baby.
Also, it can be very hard for the father to really "connect" with the baby during pregnancy because he simply doesn't have the same connection with the baby as the mother does.
My dad often tells me he didn't really become a dad or feel like one until my oldest brother was 6 months old - because before then, he had no idea what to do with a baby and just felt no connection with him. I am not saying this to scare you, but just to let you know that it's normal for fathers to be to not feel the same way about their baby that we do.
I know it's hard on you as well, and I'm not saying you should never talk about the baby - I mean, your boyfriend can hide his head in the sand as much as he wants, that won't change the fact that the baby IS coming. I'm just trying to give you a different perspective.