I don't see this ending well if you stay in the relationship. If she's not on birth control and wants a kid, I would not be surprised if she ends up pregnant. Even if she doesn't have much interest in sex, if she really is desperate to get pregnant, she will probably agree to sex only at more fertile times. Then you will be stuck with a child you made clear you were not ready for. Sadly, the child will suffer, knowing it was not really wanted by one of its parents.
It's a bad situation all around, but bringing a baby into it will only make it worse.