I'm postivie that 102 days is absolutely impossible. It just cannot physically happen, because after 63-65 days the placentas are aging and simply cannot support life any more. They die gradually, and although it is true some cats, especially siamese, can go longer than the normal 63 days, anything over 71 or 72 days and most vets would suggest a c section because the babies can die at that point. The placentas harden and are unable to pass through enough nutrients and oxygen, or filter out bodily wastes and toxins anymore.
I would guess that perhaps someone else in your household let the cat out and got her back in without telling you? Or maybe she snuck out and back in unnoticed?
Either way, it does sound like she is due soon, but I think it is a good idea to watch her rear end very closely and see if there is any discharge, it may be important to her health. If you watch her long enough, maybe lay with her for an hour or sometihng, and get a clean papertowel and just dab her vulva you can see if there is anything and what color.
Good luck, and I do hope you have her spayed afterwards