First off - neither of you should be getting igm's done. They are a very inaccurate test for herpes and you absolutely, positively can not be assuming you have herpes or being diagnosed as having herpes from them!
http://www.medhelp.org/posts/show/248394 is a prior post by HHH that goes into details as to why it's a poor test and why to ignore its results.
for under $3, your provider can order the herpes blood testing toolkit from www.ashastd.org to get up to date info on herpes blood testing - they obviously need a refresher course on it!
Your gf has hsv1. you do not. You do not have to continue taking any valtrex. should you get an obvious cold sore then yes but odds are that you really don't have hsv1. The two of you should discuss about precautions for when she performs oral sex on you too.
grace