Nursing jacks up your hormones so many women don’t start menstruating again until after they quit nursing. Of course, every woman is different. But, while is does DECREASE your fertility, it doesn’t mean you can’t get pregnant.
You’d have to go slow, or else the baby would get knocked loose or smushed between the two of you. But it should be possible. And if you’re both so passionate that you can’t even wait until the baby is finished… well then God bless!