Well, clearly he is either very stupid or he actually wants a baby.
does he think that the fact that he does not want a baby means that his sperm will magically turn around and swim away from the ovum? Now then boys, let's leg it, the Boss said no more babies! 
That said, how do you - really! - think he will react when you get pregnant?
have you been crystal clear about it? - I will not take the pill, if you don't want a baby, use a condom. If you choose to not use a condom we are not protected against pregnancy and if I become pregnant, I will KEEP the baby. I will not tolerate one word of complaint from you about it if I get pregnant, because you are making this choice right now. Do you understand?
And don't stop until he confirms that yes, he understands.
You really really need to talk about this and keep talking about it. You need him to confirm verbally that he fully understands that him not using a condom means pregnancy is an option and that at that point, it is a done deal.
I mean, clearly he knows this! But you need to break down this crap about I don't want a baby I'm not using a condom. It's one or the other!