Working until due date

My initial plan was to start my leave 2 weeks before my due date, use 12 weeks of disability and another week of PTO. So 13 weeks total. But according to my HR department, it takes 7 days for disability to kick in and I wouldn't get paid my first week of leave unless I use PTO. which knocks it down to 12 weeks off. Then what if my baby is a week late from due date?! Then I only get 9 weeks with him... UGHHH. Should I just work until due date? 😭 I have a desk job but I'm really mentally checking out here. *sigh* Do you other mommies have this figured out?