How do I find and correct the missing feature in my code?

My hangman game code is not giving one feature expected of it. All other things work fine but the lines are still blank even after giving so many letters so I don't know which letters I've guessed correctly and how many letters I have left. Please, help me figure out what's wrong with it.

import random
from word import words
import string

def get_valid_word(words):
    word = random.choice(words)
    while '-' in word or ' ' in word:
        word = random.choice(words)
        
    return word
    
def hangman():
    word = get_valid_word(words)
    word_letters = set(word)
    alphabet = set(string.ascii_uppercase)
    used_letters =set()
    
    while len(word_letters) > 0:
        print("You have used these letters: ", " ".join(used_letters))
        word_list = [letter if letter is used_letters else "-" for letter in word]
        print("current word: ", " ".join(word_list))
        user_letter = input("Guess a letter: ").upper()
        if user_letter in alphabet - used_letters:
            used_letters.add(user_letter)
            if user_letter in word_letters:
                word_letters.remove(user_letter)
        elif user_letter in used_letters:
            print("Already used, choose another ")
        else:
            print("Invalid character, choose another ")
    
user_input = input("Type something: ")
print(hangman())