I don't think your retention is too bad, actually. I would focus on expanding your vocabulary instead of improving retention. If I see this correctly, you are not adding many new words. But for getting better at reading you will need to expand your vocabulary a lot. I suspect this is why you feel like you are not improving. Don't forget that an SRS shows you a review at the time you are likely about to forget the word. At any time before that you actually remember it better.

Personally, I would drop Bunpro and instead spend more time reading. Nothing wrong with Bunpro, just that once you are past beginner grammar you can just as easily just google grammar points you don't know when you see them. No need to SRS them in advance.