YOU! 🫵 YOU WRITE THINGS SOMETIMES, RIGHT?!
how do you keep up with all your stories, OCs and lore stuff..? ;-; any advice on how?
Notes notes notes notes notes notes NOTES!!!!
You don't need pre-organized documents. When you get an idea WRITE IT DOWN!!! It can be on physically anything, preferably something small or part of an established notebook for note-keeping. Only after you have multiple ideas codified on paper can you, later on with a clearer head, organize and trim and expand on the ideas as necessary. My personal notes range from "four a4 pages in my general purposed drawing notebook with details about scenes, dialogue and worldbuilding condensed into short readable quotes" to "slip of paper that just has CRYSTAL COOL written on it" and with a lot of that material you can shape it into what you need. You can't shape or organize something you don't have yet.
Notes don't have to be pretty either! Its literally just something to help you remember what you thought of. If coloured stickers help, use them! If rewriting in a more legible manner in a bespoke notebook helps, do it! If your notes are all barely comprehensible doodles, who cares! As long as YOU know what you meant and you're reminded of what the idea was with said note, it's served its purpose. I know a guy who has an entire WALL in his room dedicated to just taping to it all the notes he has for his worldbuilding. Yes it looks deranged, but if it works, who cares about aesthetics. It's the behind the scenes stuff, like those "out of sight out of mind" wires for server rooms. No-one is allowed to judge you if in the end the ideas can be shaped into something satisfactory.
Also, if you have a LOT of OCs and worldbuilding tidbits, you could make a template for writing down the most relevant information. For characters this can be your standard character sheet (name, age, height, species, gender, sex, etc) or a more specialized character bio (for my characters I write things like philosophical leanings, attachment to objects, speech patterns, empathy levels and stuff like that because it helps me distinguish their voices when I write them), depending on how important the character is obviously. If you find yourself giving too many details to a random NPC consider making them the main character. For worldbuilding though, I used to write faux-encyclopedia entries for some of the concepts and items in my stories, the limit being that none of them were allowed to exceed a certain character/page limit in order to prevent me from over-explaining and also to ensure I wrote down only what's most important about them. I haven't used that method in a while but I might restart sometime soon.
Also, don't be afraid to discard things! If you change your mind about something, don't feel compelled to keep the old version for the sake of consistency. Growth, change, cutting and re-adding are all part of the growing pains in developing a story. I typically have the mindset of "before its published, it can be anything", so while you're still workshopping things, give yourself room to do literally whatever is necessary to make the story Feel Better. And, if you're doing this as a hobby and aren't planning on publishing anything, REJOICE!!! You can do literally whatever you want forever and anything can change or stay as is and it literally doesn't matter as long as you're having fun.