I don't know how to read.

Yes, you read the title correctly, no I am not illiterate.
When I say that I don't know how to read, I mean that I don't know how I 'should' read and that lack of knowledge and fear of reading the 'wrong' way prevents me from reading. I use quotation marks because I am aware of how ridiculous and arbitrary this all is.
Like many people I was an avid, advanced reader as a child - the tldr is; younger me had no problems reading, they could easily get through a novel or two a week, etc etc.
My problems with reading started in the year I discovered annotation, and fell into a state of (insert severity level) mental and physical illness. Needless to say because of such illnesses I didn't read much. In the span of 2 years I don't think I read more than 4 or 5 books, outside of the ones I read for school.
The thing is that I can't read without feeling like I need to annotate the book, in depth, and for non-fiction books as well. If I'm not annotating my brain interprets it as a sign of intellectual failing, because I 'should' be having 'intellectual' thoughts about what I'm reading all of the time, or else I'm not doing it properly. Does this take a long time, to agonise over every page? Yes absolutely, and now reading seems like something daunting and a 'task' instead of something fun to do. It's not that I'm forcing myself to do something I don't want to do, but that I've constructed an arbitrary system around the activity that makes it very difficult to enjoy it. Essentially I'm sucking the joy out of my own hobby.
Yet I don't want to stop annotating either. I genuinely like the idea of noting down my thoughts and being able to look back on them later, or to have a conversation with the book I'm reading. I believe that's why I started in the first place before it spiralled into something more intense.
What I'm asking everyone here is essentially: How do you read? For fiction, and for non-fiction. I have so many fiction and history books I would love to be reading, but am not because I don't feel like I'm able to have smart enough thoughts about them. Please give me some advice, or help me to understand how silly this mentality is.

Let me guess: you are a literature student.
It's quite common unfortunately. I know people that once they have started analysing texts they just can't stop. It's great for writing essays, because there is probably 101 things in a simple passage that you could write about (it's written that way). However, getting yourself to turn that part of your head off and just to enjoy the narrative is a difficult task. I have friends who sometimes complain about this aspect of me.
I spend most of my time reading nonfiction across a wide span of subjects, so naturally I would take a lot of notes or make a lot of annotations throughout.
Having intellectual thoughts isn't based on whether you make annotations or not, but whether you can articulate a strong discussion about what you have read. If you can articulate this, then it doesn't matter whether you annotate or not.
On the other hand, whether you can make intelligent contributions or discussions on a book would also depend on what ideas and throughs the book provides. It's for example very difficult for me to say something reasonably intelligent about a Noddy book.
I often use annotations to help me with referencing and finding the sources of the information at their precise location on the page.
I read using 3 different methods:
Academic/targeted reading, where I read specific passages within a text based on what I specifically want to find out.
Reading for leisure, where I just go with the flow of the book and not analyse anything
Reading for learning, where I read through a book and bookmark/highlight information that I find interesting that I might go back to at a later point or something that I should learn.
For fiction, I tend to read for leisure. If I am doing literature studies, I would read to learn.
For most academic textbooks and for guided learning, I would use academic reading.
For non fictions, I would read to learn but occasionally use academic reading if I know what I precisely need to find out.
As you can read a novel in 4-7 days, I wouldn't think you would need to know about speed reading. However, it's also a technique I use myself if I want to get through a lot of reading material quickly. See:
https://tim.blog/2009/07/30/speed-reading-and-accelerated-learning/
https://www.youtube.com/watch?v=ZwEquW_Yij0
https://www.youtube.com/watch?v=I_GWxFNpZ3I
https://www.youtube.com/watch?v=6ZkGFiR1434
https://www.jimkwik.com/podcasts/kwik-brain-007-how-to-read-faster/

You would be correct. I was a literature student (and will be again), I graduated high school actually, but the mindset remains.
“Having intellectual thoughts isn't based on whether you make annotations or not, but whether you can articulate a strong discussion about what you have read”
I definitely believe a part of me is seeking intellectualism for the sake of it, without really analyzing what exactly that means, because I think it makes me a more worthy individual. It’s performative in the sense that the only person I’m performing for is the version of myself I wish I was.
The reading for leisure is what I struggle with the most. I don’t think it helps that I see a lot of incredibly detailed annotated for pleasure books on line, and believe I have to replicate that because that must be what ‘really’ enjoying literature is like. These books are less of the ‘Noddy’ variety and more ‘The Secret History’, ‘Wuthering Heights’, ‘Babel’ etc.
The speed reading links are actually quite helpful, my days of reading a novel fast currently seem to be behind me, though I could probably do it if I didn’t force myself to read in such an involved way. Your breakdown of the different types of reading are incredibly helpful. Would you please be able to clarify further on what ‘reading for learning’ looks like?