If an un-spayed cat goes outside while she is in heat, she will come home pregnant. Guaranteed.
The gestation period for cats is approximately 63 days. Therefore, if your cat is intact and she has been outdoors within the last two months, I’ll bet she’s pregnant.
Pregnancy status can be assessed in pets through blood hormone assays during the early stages. During the later stages of pregnancy, X-rays of the abdomen are the simplest way to confirm the presence of fetuses. X-rays also make it possible to determine how many fetuses are developing in the womb.
Based on your description, it sounds like your cat may be close to term. I recommend that you have a vet examine her and take X-rays in order to know how many kittens will be needing homes. It is your responsibility to find those homes.
As well, talk to your vet about having your cat spayed after the kittens are born. Otherwise, you can expect to repeat this process twice each year.