No, it is unlikely for your cat to get pregnant when she is not in heat. Queens come into heat when a follicle matures in the ovary, ready to be released as an egg. Release of this egg into the uterus (ovulation) will only occur after mating. If the egg is not successfully fertilized, your cat might experience a pseudopregnancy where she shows many of the symptoms of gestation (milk from nipples, altered behavior, weight gain, etc.) without actually being pregnant.