Hi my cat Jilly has been spayed about 2 years now but she's gained weight on her tummy area, she's being extra nice, she keeps going in my sisters wardrobe and moving things about making a bed of some sorts and extra hungry? What's happening!

No.

A spayed cat cannot get pregnant, since the uterus and ovaries have been removed.
That being said, weight gain and increased appetite warrant a trip to the vet.