The best choice is to spay your cat, but if medical conditions prevent the procedure, you'll have to learn to live with it. Unspayed cats can be a handful even when they are not in heat. There are ways to cope with their extra needs, but you need patience and earplugs to make it through.
Instructions
Keep the cat indoors at all times. Do this even if she hasn't gone into heat for the first time. The less a cat has been outside, the less they want to go outside. Train your kitty to be an indoor cat. Keep her on lockdown to avoid unwanted kittens. The sooner you start, the easier it is on you.
Get the cat all of her shots, including feline leukemia. Keep her shots up-to-date even though she is an indoor cat. You never know what she might decide to do while in heat. Clearly she's not in her right mind. A cat that has always been scared of the great outdoors might suddenly decide to launch itself out an upstairs window.
Get a second cat while your kitty is still young. Unspayed cats are more territorial. If you ever want a second cat, it is easier to integrate them while they are still young. Unspayed cats tend to be needy and demanding. Strongly consider the possibility of a second female cat if you plan on being gone often.
Shut the cat in a quiet room if her crying gets to be too much. Without much social stimulation she should likely just fall asleep. That is a blessing for both of you.
Talk to your vet about calming products for your unspayed cat. Sprays and plug-in devices that emit calming pheromones are available. Try these when your kitty seems overwhelmed. If being in heat is wearing her out or if she is going through a particularly needy phase, see if she responds positively to these products.
Discuss hormone therapy options with your vet if you're concerned about pregnancy, or simply can't take it anymore. It might be more expensive and more trouble than it's worth depending on your cat's personality. There also may be concerns about the long-term health effects of hormones.
Keep a close eye on your cat's health, but realize that her cycles change. Have good communication with your vet. False pregnancies are possible and so are hormonal changes. Your vet can help you decide what, if anything, is worth worrying about.