Well that's good. You know more Japanese than me.
All I can say is that you should start reading stuff in Japanese and check around on other Japanese language learning forums for recommendations on which grammar books to choose.
Check these out if it's possible. I have read people who are very fluent recommend these:
"An integrated approach to intermediate japanese"
"Authentic Japanese: Progressing from Intermediate to Advanced"
Look into these books too:
"An Integrated Course in Elementary Japanese"
"A Dictionary of Advanced Japanese Grammar"
http://grammar.nihongoresources.com/doku.php - This one is available for free as a download too.
Last edited Mon, 04 Jun 2012 17:43:38 +0000.