BIG mood :'D I'm also the sort to get overwhelmed by theories and guidelines - I remember at some point looking at a plot structure like the 3 act structure or the hero's journey or something and having to fill out the call to adventure, the refusal of the core, the climax, the darkest hours etc etc and I was like NOPE.
I guess my two cents would be:
1: Think of the rules as tools, rather than checklists
If you're making a sandwich, you don't have to get out a knife, a chopping board, a pan, a spatula, a lemon juicer, a garlic crusher and the kitchen sink from the get go. Chances are you won't need most of them and then you'd just have to pack them away for no reason.
Just start making your sandwich, and when you get stuck (oh, I need this tomato sliced), you go find a tool for the job (I know, I need a knife!).
Same with writing. I totally gave up trying to use plot structures - I just wrote whatever I wanted until I realized my story is just my characters hanging around and doing random stuff; there's no real direction or sense of progress. That's when I went online and look for a tool to fix my problem, and then I bumped into plot structures, my old enemy, but this time it came to me as a friend. And even then, I don't follow them to a T; I just kind of use them as a point of comparison when I feel like my story lacks forward momentum :]
2. It's okay to reinvent the wheel
Sometimes you read some advice but it just doesn't click with you, but them you go off and write your own thing, and you kind of rediscover the advice independently on your own. I personally find this is the best way to actually understand a piece of advice and when/why it's applicable
I use plain text and word documents and don't touch any of that fancy software I've heard people talk about (like Scrivener, WorldAnvil etc) - I get overwhelmed by the systems they use! But that doesn't mean I don't have systems; eventually I see patterns in the way I write and establish conventions that make things more organized and easier for myself. Some of my systems resemble the systems built in to writing software/common writing advice. But I only get used to them by developing them myself from the ground up.