After first noting that we can't help with homework because your teacher needs to see what you can do and not what we can do, I will say that I agree with you. I can't see any useful difference between 1 and 2, and find 2 to be awkward. That makes this assignment rather pointless, in my view.
However, perhaps another user will find a compelling difference between 1 and 2 and will make a strong case for 2.
I will also tell you that your first sentence won't work. It would work with "she has been worrying" but not "she had been worrying."
Student or Learner