Yes, ParisDean, we are thisclose to being out of material from the books. HBO has milked that source dry. Meanwhile, Martin is too busy partying like a boy who wasn't popular in school but now is the IT thing and therefore he hasn't finished a book in over two years!!
But I digress.
There are a few more things that could be brought in from Book 5, but they were very small and the show seems to have diverged from a way to seamlessly add those things in as it would require brand new characters with ties to old, well known ones.
In terms of Jon Snow, he was ambushed just like in the books and readers do not know his fate either. All of the juicy stuff (IMO) HBO has shown and now must go off their own creative direction and how Martin plans to end the book series.
We aren't ahead of the books yet but starting this season we sure will be probably as quickly episode 1!! And as a reader, I'm happy to be enjoying the show "spoiler" free