I think "Good Enough" is about Amy being in love with someone again but also being "Under the thumb". I also agree with what was said before, about Amy not feeling that she is good enough for her love interest.
I also think that it signifies that she feels she is being defeated.
She's still waiting for something to happen to her and make her happy again
by the lyrics "I'm still waiting for the rain to fall, pour real life down on me".