If you're serious about learning Japanese, you need to move there. I'm not sure there is any other way to properly understand all the uses of "kakeru" besides simply hearing them all hundreds of times to the point where you just "feel" when it's right to use it. There's just no substitute for immersion and pure exposure.

I studied Japanese at one of the most demanding University programmes for two years intensively (an hour of class, another hour or two of language lab time, another two or three hours studying PER DAY) but I honestly did not really start internalizing any of it until I lived it every day. It was watching TV, hanging out in bars, hearing the subway announcements, and texting my friends that actually let me become fluent.

It's like any other skill, actually... could you learn painting by reading about it but not using a brush all the time? Could you learn gymnastics watching demonstrations but never trying to do a flip? I'm not saying you don't practice - it sounds like you've worked very hard - but immersion is a completely different kind of experience. If there's any way you can, don't give up on your dream Move to Japan, even just for a year. Once you really internalize the language, it will be a part of you forever.