Hi Bevie-- Wow, over 5 years, yippie! I'm sure the fears never go away.
I don't know that much about the question that you've asked-- I doubt that there's much data. I would make the uneducated guess that you're pretty far out of the woods given how quickly Her2+ bc tends to recur vs. Her2-.
I'm also including a link which was in the 'supplementary materials' part of the Herceptin study that was published last year in the New England Journal of Medicine. It breaks down the study results by hormonal status, as well as number of nodes. It doesn't have the history that would be applicable in your case, but it might be interesting to others who are following this thread (the interesting tables are on the later pages).
http://content.nejm.org/cgi/data/353/16/1673/DC1/1
Good luck with your tests.
Jen