Based on your listing with finishing Minna no Nihongo 1&2, it should put you about N4 level according to this customer review of the first and second book.
I am also working through Japanese the Manga way for grammar. Despite the romaji, the content is pretty solid. Especially if you have an interest in reading manga (which I do and currently reading しろくまカフェ). Though the negative is that there are no exercises which from what I read, is what you want in a textbook. So maybe just do a quick read if JTMW still peaks your interest.
As for exercises, you can always try the Nihongo Challenge for JLPT N4 Preparation: Grammar & Reading Practice book. Then afterwards you can tackle the N3 Sou Matome grammar or Kanzen Master N3. A great reference source for grammar just in case any grammar points aren't clear is the A Dictionary of (Basic/Intermediate/Advanced) Japanese Grammar series though I'm sure the Basic (Intermediate maybe?) will be enough at this stage.
Finally, I agree with Stansfield123 about getting more listening in. I have terrible listening skills so this is one of those things I work on. Speech is my worst, which isn't really a surprise because I don't ever talk to anyone lol. Hope this helps.
I am also working through Japanese the Manga way for grammar. Despite the romaji, the content is pretty solid. Especially if you have an interest in reading manga (which I do and currently reading しろくまカフェ). Though the negative is that there are no exercises which from what I read, is what you want in a textbook. So maybe just do a quick read if JTMW still peaks your interest.
As for exercises, you can always try the Nihongo Challenge for JLPT N4 Preparation: Grammar & Reading Practice book. Then afterwards you can tackle the N3 Sou Matome grammar or Kanzen Master N3. A great reference source for grammar just in case any grammar points aren't clear is the A Dictionary of (Basic/Intermediate/Advanced) Japanese Grammar series though I'm sure the Basic (Intermediate maybe?) will be enough at this stage.
Finally, I agree with Stansfield123 about getting more listening in. I have terrible listening skills so this is one of those things I work on. Speech is my worst, which isn't really a surprise because I don't ever talk to anyone lol. Hope this helps.
Edited: 2016-05-14, 1:19 am