The OP was asking if the word they added in red in the main post had been omitted from the original sentence.
@v0031 Titles should include some/all of the words/phrases you're asking us about. A good title for this one would have been:
This is the proudest and happiest [moment] I've ever felt.
Your post should have looked something like this:
I think the word "moment" should appear after "happiest" in the following sentence:
"This is the proudest and happiest I've ever felt."
Am I right?