She wrote a new book not too long ago, called "The Tales of Beedle the Bard". It's story takes place within Harry Potter's world of wizardry, and uses lots of references from the Harry Potter series. I haven't read it myself yet, but I heard it's pretty good.
And what makes you think she didn't want to write her last HP book, or made you think she was rushing to finish it? I thought it was a great finale, personally.