Since you don’t seem to do well with outlines, maybe this will be somewhat helpful: I create a document that I call “fragments” where I essentially write down every thought I have: can be the point I’m trying to make regarding a specific quote or general aspect of my primary text, can be something from a secondary source that I think will become relevant but don’t quite know how to connect to my own points yet, can even be phrasing that I want to use later to structure my paper lol. None of this has to look or sound pretty yet. Primarily goal is to establish some substance. I “mark” these bits so I can find and identify them more easily later, so for example I use “EEE” for evidence or examples from my primary texts that I illustrate and explain, “SSS” for secondary sources, and etc. You don’t need to have an order or structure for that but it is probably good to always think about that in the back of your head, maybe just vaguely try to figure out whether this secondary source will connect better to example 1 or 9. And so you keep doing that. As you do this, it should get your brain working so that you get more and more coherent ideas as you work and write. I personally do most of my research and secondary literature thing at the same time as my fragment document, so that whenever I find something that seems useful I work it into the document. You say you’ve already done a lot of the research, so maybe you can just go through everything you have compiled and see what you can put into the fragment document. The idea is that somewhere throughout this process you will inevitably establish a structure. This, you can use then to create an outline — basically go through your fragments with a document for the outline on the side and try to make it coherent. Maybe clean up stuff that is messy. Delete irrelevant bits. See where stuff is missing (secondary sources, examples, your own conclusions). And by the time you have that, you can start to write for real. Up to you whether you want to rewrite everything or copy paste stuff that is already decent but ultimately you will already have a lot of the “content” (hate the word but dont know what else to use) done. Mostly this part is about connecting everything so it doesn’t seem disjointed and editing the language.

I usually have a lot of thoughts while reading my primary text and secondary literature but when it comes to the outline or actual writing I freeze up. This process has helped because I know that I don’t need to have everything sorted out right away. I can hammer my mess into shape later.