I know someone who learned Japanese only with learning books and could read text books few month later. With motivation and perseverance you can do everything !
He recommended me (I still haven't bought it) this grammar book, saying grammar was very nicely explained and classified :
A Dictionary of Basic Japanese Grammar (Vol. 1)
(nihongo kihon bunpou jiten)
By seiichi makino & michio tsutsui
Editions THE JAPAN TIMES
ISBN-10 : 4-7890-0454-6
ISBN-13 : 978-4789004541
I looked at amazon, user's comments are very good.
You can see 2 scanned pages from this book here :
http://chiba.davidcochard.fr/apprendre-le-...-bibliographie/
look for "page 1, page 2"
Looking for "must" in English index gets you to these 2 pages.
Editor's preview :
http://bookclub.japantimes.co.jp/pdf/0454.pdf
Vol2 exists too (which is much harder than "intermediate"):
A Dictionary of Intermediate Japanese Grammar
?????????, ??? (nihongo kihon bunpou jiten, chuukyuuhen)
Authors : Seiichi Makino & Michio Tsutsui
Editor : The Japan Times
ISBN : 4-7890-0775-8
As the titles says, it's only a dictionary when you are looking for grammar, not a linear learning course.