The problem
You want to communicate in a second language, but you can neither understand nor form anything approaching a level of conversation that you’re subjectively happy with.
The solution
Go out there and talk and consume content anyway.
There’s no secret shortcut that I can tell you, and I can only relate as to my own journey on learning Japanese. Whether you think my Japanese is good or not is up to you, and I have a lot of content on my YouTube channel including longer conversations with native speakers to show you what I can do:
I am constantly amazed at the level of Japanese people can speak despite never setting foot in Japan. I say this due to so many of my own insights and eureka moments occurring during conversations with Japanese people and hearing a word get used in context that at least starts to cement that word or manner of speaking in my head.
I have spent many hours studying from books and these hours were not wasted. There are particular areas of Japanese, such as kanji, that I think need this type of study. My comments above as a JSL speaker apply of course to this as well: I simply don’t think it is possible to ‘know’ how to study a language at 100% effectiveness to become native-level. You can throw whatever studies, experts or whatever at me to try and disprove this. I’ll consider evidence but fundamentally it goes beyond epistemology, linguistics or any form of human knowledge.
However, the pattern of studying Japanese often followed the cycle of book study, content consumption and then playtesting in real life: actually getting out there and talking to Japanese people and trying to have a conversation about anything.
That’s the advantage of living in Japan, to do anything involves interfacing with Japanese and so you’re in a sense forced into these interactions. Doing reps everyday reinforces your learning in ways you don’t notice and then it compounds over time.
As an example, I used to try and read Japanese books when I had free time in the library while I was in Japanese high school. I would also do as much school work as I could (while in class of course, I wasn’t doing any Japanese homework because that was important TV time) which for the first 6 months or so involved writing hundreds of lines of dictation from the teacher. I had no idea what it was I was writing and didn’t really go back and read it at any point, but I saw it as laying the groundwork.
I consider myself a fairly adept user of English, and remembered that a large part of that came down to reading a lot of books and writing a lot of short stories/essays. So I figured surely I have to do something approach that body of work in a second language as well.