Just some thoughts and encouragement! Congrats on finishing Genki I!
Iteration: when you learn grammar and vocab, you have to see it again and again in different contexts for it to stick and make more and more sense. Keep iterating, and by the sounds of it, find more level appropriate material. Challenges are good, but if the challenge level is too high, you can’t even tell if you’re making progress. Genki 2 will help, so keep going, but don’t expect reading to get easier until you’ve grappled with a lot of reading. That’s just the way it is! The good news is if you read a little bit of something daily, then over time, it will get easier and easier to read more in the same amount of time. Reading more makes reading more easier. We normally have to do other language activities to support that and I’m not diminishing the importance of that, but don’t wait for or expect anything else to do that job. It took me a long time (years) to realise that and I wish I had learned it much sooner.
Expectation management: with N5 grammar, the most level appropriate material you can read is Tadoku graded readers (for learners), where things have been simplified to stick to the grammar you know and the vocabulary is also restricted to a small set. It can still be tough, but you can get that kick from seeing the grammar you know in action. You’ll still be learning a lot of vocab at this stage.
If you’re bored by graded readers or moving up from there, your best source of native material will be to get into the ABBC and read with the support of the club, or read on Satori and make it through with the help of the notes there. No matter what, at first, this will probably be a struggle and be a lot harder than Tadoku. But you will notice making progress after making it through a full ABBC pick, or a full series on Satori. See ChristopherFritz’s post on deciphering vs reading .
For films at natural speed - this should be a fun side activity with low expectations right now. You’ll need to cover a lot more vocab and grammar and get in a lot of listening practice before this starts to feel like you’re making any progress. And that’s not fair because you will be making a lot of progress. Break it down and go for simpler things and work your way up: audio for Genki exercises and reading section, audio for Tadoku/graded readers, audio for Satori episodes, manga read throughs, podcasts in Japanese directed at learners with transcripts, youtube videos in Japanese directed at learners, youtube videos directed at children, shorter films or anime episodes, easier films, most films.
Bunpro sentences - I haven’t used it, but outside of a story, reading isolated sentences is a lot harder. You’re missing the context which allows you to make connections easier. Remembering the word for “fear” is a lot easier when you just read a sentence that might make the character feel afraid.