ObsidianMD

Good morning (excuse my English, it's not my first language), I am very disorganised and forgetful, I always live in a state of anxiety because if I don't make any reminders (for this I use 'saved message' onTelegram) I literally forget appointments, deadlines, so: I always live under persistent stress due to the strain of keeping a lot of things in mind. Of course I own a paper agenda, but I forget to use it. I'm looking for something that keeps in 'his mind' the things I should keep in mine, so that I can invest energy in other tasks. In essence, I feel completely unstructured.
Obsidian, inevitably, intrigued me: the idea of looking at one's brain from the outside is an enviable condition, rather than being inside the terrible tangled cage that is my brain.
I saw some tutorials, some of which are very long and some of which are super-fast. I began to think that it is not the tool, but the way one memorises and organises one's notes (in the broadest sense) that makes the difference. I'm afraid that if one has a lot of confusion in one's head, and is always working in a state of emergency, with the fear of having forgotten something, this is the real problem, and there is no Obsidian to help. How could Obsidian help me? And also: is there any video or document that teaches how to learn it properly?
Thank you very much for your advice.
p.s. Is there any possibility to sync Obsidian with laptop, mobile and tablet avoiding (for the moment, then if I start using it regularly, I'll happily subscribe) to pay the 8$ monthly fee, also avoiding using Gdrive or any other nosy tool that overbearingly imposes its policy on users?