To make her more comfortable with you, give her treats when you check on her. You can put some tuna on a spoon and let her eat it as you pet her with your free hand. This will make her more comfortable when you change the litter with her precious kittens there. Otherwise, she may get very protective and if she can't move the kittens when she feels uncomfortable, she might get mean with you and, if that happens, you will not be able to change the litter.
I don't want to sound alarmist, but if she doesn't have kittens soon and if she will let you, lay her on her back on your lap and tap her belly. If nothing happens, she should be fine, but if her belly seems to ripple like water, then you need to call a vet and have her checked for FIP. Cats with FIP will look pregnant and have mood swings (they are sometimes friendly and sometimes angry), too, so I really think it would be a good idea to check her to make sure. Also, if you do find she has FIP, please notify the neighbors to have their cats checked because it is very contagious among cats. Certain parasites can make a cat look pregnant, too, and most of those can be cured pretty simply. I had one cat with FIP many years ago and last year my spayed female had parasites and I was about ready to let loose on the place that spayed her because I thought she was pregnant.