Well, first it depends on your definition of fluent. What Nosferatu is pretty much head on for the standard definition of "fluent" which I personally think is very low. (IE, you probably wouldn't be able to interpret at a high level, but can live your life on your own in Japan). I lived in Japan for 7 years and still had troubles with certain topics. The news and newspapers, are particularly difficult to understand 100%, whereas 70-80% is pretty attainaible.
6 college semesters is nowhere near JLPT 1... in most cases, just barely able to pass 3 really.
Langauges are weird. Some people catch them, some don't. I can really only comment on my own experiences, and those I've witnessed. For me:
-3 years in university (this was over 24 credit hours though mind you -- my 3rd year I took two courses per semester)
-3 months in an exchange trip. This is where you would 'double-up' so to speak. I took 3 courses, and studied about 3-4 hours a day
-Back in university, I finished all the normal classes so did private study and turned work into a professor.
-1 year in Japan, self-studying (I had a job at this point) and I was able to pass JLPT 2. Some year or so after this is when you start feeling fluent, although Japanese people will tell you after 2 years of university that you "speak great Japanese."
Note that to pass Level 1, you will need to be able to read Japanese like you read English. Pick something up, read it and digest about 80% of it (tiny details included) in one pass. Get the other 20% or so in the 2nd pass. This is very hard - by far the hardest part on the test, and the grammar is sick as well.
As before, it's different per person. To be honest, I think the biggest variable is how you spend your time in Japan. You can really excellerate, but it doesn't happen by accident. I spent a lot of weekends locked away in my room.