We don't want to let her outside because we don't want her pregnant again. We have to wait 40 days before the Humane Society will fix her. Is she susceptible to becoming pregant right now while she is nursing?Thank you for your answers. I will try my best...she runs from door to door crying...won't use her litterbox...and RUNS out the door every chance she gets...

Keep her indoors and locked up....) She can get pregnant right away, even thou she is nursing. Good luck with keeping her indoors.

YES I know from experience about my cats

Yes, she can. I would recommend confining her and her kittens to a room with a door, to prevent her from being able to dart outside under your feet when you're distracted. If she's used to having outdoor access, you can increase her chances of using the litterbox by providing her with two boxes, without lids or covers, and by using Cat Attract litter (from the pet store), and sprinkling a little bit of dirt and shredded leaves from where she usually goes outside over the top of the litter. Scoop soiled litter and solid waste twice daily, to keep the boxes extra clean - cats with outdoor access are free to move to a clean spot of the yard any time, so you'll need to make sure to keep her boxes clean since she doesn't have the freedom to select a new spot to go for now.