I don’t mean to sound presumptuous, but that sounds so much like me. It’s so relatable. 
I’m probably not at 6000 hours yet, but having way more input than output, learning rare words just because I want to and being able to write fairly easily but not really speak? Very much my life too.
I guess the main differences for me are that
- most of my input is from anime, and the rest of it is all over the place: I read a lot of dictionary entries, articles and studies on grammar and usage and the occasional news article, and I watch VTuber streams. I personally think that streams are relatively helpful for conversational Japanese because they allow me to see how people speak to each other in a fairly natural way, particularly when more than one streamer is present, though of course, speech tics may occasionally be present if they’re part of the streamers’ personae. That aside, I also need to remember that what I hear may only be appropriate for informal conversations, and I may have to convert what I hear into a more polite form afterwards.
- I started practising output fairly early on because I have a fluent friend studying in Japan, and I send him messages in Japanese rather often. That also helps me to improve because he can tell me if I’ve made a mistake or if I’m saying something in an unnatural way, particularly since he (unlike me) regularly has to have conversations with Japanese people. However, all this only happens over text, so it doesn’t help me much with speaking.
Am I conversationally fluent, at the end of the day? Uh… not exactly, because I know there are still plenty of words I get stuck on, or which I’m left searching for in my head. I find that it’s still easier for things to flow when I’m writing, and honestly, words need to come a lot faster when you’re in the middle of a conversation than when you’re writing, even if you’re doing so via a messaging app. There’s a lot less pressure too. However, I managed to carry on with two Japanese teachers for 5-10 minutes the other day while understanding almost everything and getting my own thoughts across, so I guess I’m on my way there.
I’m not sure about a ‘good’ conversation in the sense that I still occasionally need to find other ways to phrase my thoughts because I get stuck, but I guess my results so far have been decent, though I’m far from being completely comfortable. To sum up, particularly if conversation is your concern, I’d say you need
- Plenty of input and listening practice – this is more for the sake of getting used to how phrases and sentences are formed, and listening practice helps you to understand conversations at their normal speed
- Vocabulary – this is something you can (and perhaps should?) build using input, because honestly, memorising a list of new words without having a sense of how they’re used in reality is quite pointless, if you ask me. It’s much better if you’ve seen words being used and understand them before studying them.
- Grammatical knowledge – you can build this through input, but you can also use textbooks and services like Bunpro to fast-track yourself to the point where you have enough knowledge to form basic sentences. However, in my opinion, you shouldn’t expect to be able to use grammatical structures fluently by memorising translations off sites like JLPT Sensei. Always understand first. That’s what I believe.
The last thing you need, once you have enough knowledge to form a few sentences (you don’t need a lot, just some – I was already writing messages to my friend when I was about 50% of the way through my first textbook, which had probably got me to around an N3 when I reached the end of it), practise as much as you can. However, I’d really suggest that you get people to correct you, or that you imitate common patterns very closely initially, because otherwise, you’ll end up producing a lot of stuff that makes no sense. This is not meant to instil a fear of output practice in you, quite the contrary; what I’m suggesting is that it’s far more productive when you have someone to tell you if you’re successfully communicating. I would not have progressed as quickly without my friend’s advice and corrections. You can make use of the grammar and language question threads to check if what you’re saying is natural.
That aside, well… practise, practise, practise. That’s really about it. Once you reach the level where you can consistently form coherent sentences, you should be able to start picking up new words from input with the help of the dictionary, and you’ll have a better idea of what’s natural even without being corrected or evaluated all the time. I may not be all the way there in Japanese yet, but I’m still speaking from experience: I’m doing a master’s degree in France now, entirely in French, and I started learning it when I was 13. I reached the C2 level 5-6 years after starting. (I was slower back when I didn’t know how I learn languages most efficiently.) It’s basically always the same thing: build enough of a base, then accumulate knowledge and broaden your experience with input while getting more expressive through output. Eventually, you’ll be fluent.
)
So a VERY long time I guess?
. I still have miles to go, but feel pretty at ease having the language as Japanese.
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