I’m great
No complain
Not bad
Very well
I’m happy
Perfect...
Now that's an answer you won't hear very often.
When I say "perfect", the other person's eyes open wide and they have a surprised look on their face.
They can't believe that my life is perfect (of course, it's not perfect, but the answer is funny and it's also a very positive answer.
Try it and see what kind of a response you get.
This might not be helpful, but it is funny.
In Ireland the normal response to "How are you?", is "How are you?".