Is it possible to endlessly add key:value pairs to a dictionary based upon user input?

I have a dictionary called "user_database" that holds users, and a variable called "registered_users" that increments as the input is called in a "while True" loop. How can I endlessly add new users to the dictionary as the inputs are entered?
this is what I have, (BTW I am a beginner at python)

user_database = {
    "username": "my_username",
    "password": "my_password"
}
 
registered_users = 1

def register_user(user_database):
    if user_database:
        while True:
            for i in range(3):
                registered_users = i += 1
                username = input("Enter your username: ")
                password = input("Enter your password: ")
                user_database[f'username_{registered_users}'] = username
                user_database[f'password_{registered_users}'] = password
                print(user_database)
                continue
register_user(user_database)

here is the output:

Enter your username: sunshine
Enter your password: sunshine123
{'username': 'my_username', 'password': 'my_password', 'username_1': 'sunshine', 'password_1': 'sunshine123'}
Enter your username: sunshine_2
Enter your password: sunshine555
{'username': 'my_username', 'password': 'my_password', 'username_1': 'sunshine_2', 'password_1': 'sunshine555'}
Enter your username: 

It is not adding A NEW key:value pair on EACH entry, its simply replacing the extra one.
I want to add a new key:pair upon each username & password input entry.

I have tried update() and It did the same thing. Although I may have used it incorrectly.

>Solution :

Something like this would do what you would want:

user_database = [{
    "username": "my_username",
    "password": "my_password"
}]
 
registered_users = 1

def register_user(user_database):
    global registered_users
    if user_database:
        while True:
            registered_users += 1
            new_user = {}

            username = input("Enter your username: ")
            password = input("Enter your password: ")
            new_user[f'username_{registered_users}'] = username
            new_user[f'password_{registered_users}'] = password
            user_base.append(new_user)
            
register_user(user_database)

In the following, the registered users are saved in a list. In this list, there are dictionaries for each user containing a key for the username and a key for the password, which is entered in the while loop. You would want to find a way to break out of the while loop yourself, otherwise you will keep going on forever. This is simply done by adding a closing condition that executes a break. For good measure, I have added that the variable registered_users is uses the global variable.