When in heat, cats are more demanding, seek attention, and become very vocal. Female cats yowl to advertise their receptivity to males, while males yowl to gain access to females.
Many would say that cats are independent and don’t care so much about their owners, but cat parents know this isn’t true! They love their humans and want a lot of attention from them.
Many things can cause stress in cats, but, this usually has to do something with a certain change in her environment. Check whether she shows some other symptoms of stress in her, such as refusal to eat, not going to the toilet, shaking, etc.