Cat Shelter Box - Weatherproof Outside (Elm Park RM12)

Hi all,
I have a stray cat that visits me. I have cat allergies but I'm becoming very fond of her.
I bought food, treats and cat flea repellent.
She doesn't like to be held or touched or like loud noises as she scares easily.
She sits outside my back door and comes in often but I have to leave the door open as she's afraid of being trapped inside.

I would like to ask if anyone has a cat house/box or some sort of waterproof covering that I can make her a home outside especially for when it rains. I feel so sorry for her she's a beautiful black and white Tabby but so afraid.

Would appreciate all the help. Thank you. Sue