Feeling like a fraud is a feeling. Your finished work is evidence. Put them side by side.

That sense of not really belonging does not check itself against anything. It runs on the inside view, where you see every shortcut and every lucky break, while everyone else sees only what you produced. Both exist, but only one of them can be examined. The feeling will not disappear on command, and it does not get a vote about what you have already done.

Keep a plain list of finished things: dates, what it was, who for. When the feeling shows up, read the list instead of arguing with yourself. You are not trying to win the argument, just to have the other column in front of you.