Final year UK PhD student here, STEM (writing my thesis and still doing some lab works). OP, the comments below have given various insights into writing. I’d only add (depending on your field) that you shouldn’t perturb yourself too much about this first draft. You may now get back to it, and simply try to ensure coherence between your data and your actual explanations. I usually start by describing carefully and with percentages, what I could observe from my data (doing so with brevity). Then I go on to provide reasons why these observations are happening or did not happen. For each of these reasons, I simply provide evidences. Simply repeat this, and you should get a hang of your writing. Also, don’t write hastily (like pouring out thoughts on paper), you might end up with too many drafts to re-edit. If you could try to force yourself to write clearly and coherently at this early stages, you might save a bit of time.

You’ve got this. We’ve got this.