Your cat might be having a common cold. Besides her sounding congested and not showing discharge, she might seem uninterested in playing with you, she could meow more, and her appetite might decrease.
You should ensure your kitten gets plenty of rest in a warm, comfy environment. Also, she needs to drink a lot of water to compensate for the lost fluids. You can try using a humidifier to help your cat breathe easier, and to encourage her to eat.
Allergic reactions might be a reason why a cat sounds congested (but no discharge!). Additional symptoms of allergies are coughing, intense scratching, meowing, and even diarrhea and vomiting.
If you suspect that there's a foreign body in your cat's trachea, you need to take her to the vet immediately. The veterinarian will probably recommend to hospitalize your cat, to be able to closely observe the process of the foreign object in her trachea.
There’s also a chance that a cat that sounds congested and shows no discharge will have a heart disease. A cat suffering from a heart condition will have trouble breathing, since the fluid will be accumulated in her chest cavity.
Proper treatment in the early stage of the heart disease will decrease the chance of further damage to a cat’s heart. The vet will undertake chest x-rays and a heart ultrasound to determine the exact state of heart disease in your cat.