I tried learning on my own for 18 months before going to Japan in late 2019.
I just couldn't figure out the grammar. I think I didn't actively practice "creating" it enough - too much reading, not enough reproducing.
When I got down on the ground, my vocab was fine, I had enough Kanji to get around reading shop signs and menus etc (about 400 most common kanji) but I just couldn't conjugate verbs well enough to have proper conversations, or to discern which of multiple homophones the person speaking meant (every two syllable word in Japanese could mean like 17 different things lol). And that sucked. It was enough to impress the people I was with, though, lol, and I did have some lovely experiences where people indulged my shite attempts.
Haven't done much in the 2 years since, I should get back on it I guess.
Also, if you haven't been, go. One of the best places I've ever visited. I'm not into anime or manga or some kind of Japanese culture worshpper at all - I went purely for a sporting event with friends. But by the time I left (17 day trip) I was all in on Japan. The people, the landscape, the history... it all blew me away. Also... further you get from Tokyo the better it is.