Yep, it’s crazy. A friend of mine did this and it didn’t turn out so well, she had a late miscarriage which was heartbreaking and their relationship crumbled.
Pregnancy, birth and child rearing is testing even on the strongest of couples. You don’t know this man at all, it takes years to fully know someone. I take it you also haven’t even lived with him. I understand that your clock is ticking but I would strongly suggest looking into alternatives or at least giving it a year with this man before you jump in head first.