Surely you can write one word, even if it's "The" or "If" or "A". And if you've written one word, surely you can write another.
Voice is a skill to be developed, like any other writing skill. Give yourself permission to stretch it and challenge it and expand it and enhance it.
Can you see ways to redefine "enough" and put it within your reach? Can you see ways to feel like enough right now?
Today is the fifth Tuesday of the month, which means that my answer to this heartfelt letter is available exclusively to my Patreon patrons.
There is no absolution; there are no clear-cut rules that you can strictly follow and thereby relieve your anxiety. There is only you, doing your best.
When you incorporate your research into your story, do it with a light touch. Keep your protagonist's or narrator's perspective at the front of your mind; don't harp on the things that they will find unremarkable or irrelevant.
Writing marries intuition to intellect, and sometimes the intuition part means you just know when the thing is done and no amount of hacking at it will make it not be done.
Our society heaps so much guilt and shame onto sex and sexuality, but a writer who breaks past that to celebrate and empower their own sexuality can empower their readers to do the same.
This excessive concern over a minor matter sounds like the product of an anxious aversion to declaring the book finished.
Your feelings of envy are harming you by making it hard for you to achieve a degree of self-defined success that might lead to you feeling less envious.