hi! my advice is to do what makes you happy and try to free yourself from others' expectations. so ive been writing nsfw for something like 10 years now, and at the beginning i very rarely posted it. i was just throwing shit in my notes app and if i was very enamored with something then i'd clean it up and post it. you don't gotta post everything! it can just be for you (and/or your close friends. highly recommend having a friend who will hype you the fuck up AND do helpful constructive criticism). the tldr of this is just do whatever you want lol

as far as worrying how it'll be received if you do decide to post, i think to some degree there's stuff about sex that you innately know if you've had sex or been very intimately involved with another person irl - like how much space there is between you when you kiss or what angles your body can bend at or whatever. if you don't have that experience, it may not come naturally to you, BUT it is possible to fake it with RESEARCH!!!! look at what you like about others' work (visual or written) and try to emulate that. it's completely okay to use porn as a reference or ask for assistance. take this with a grain of salt, but i also think it's helpful to examine what you don't like and work backwards from there. as a personal example i don't vibe with super porny dirty talk dialogue, most of the time i think it sounds stupid or funny, so that's not gonna be something in most of my work because my focus is on realistic dialogue, emotions, and sex-as-character-study.

you mentioned worrying about authenticity - firstly, anyone genuinely judging you for this is not worth listening to, you do not need to appease the imaginary audience in your head preventing you from even writing in the first place. this is hard! it's really easy to talk yourself out of something like this because ahhhh what if someone doesn't like it. well. what if someone does? you won't know until you do it! secondly, experience comes with age, so you really don't need to do everything perfectly on your first nsfw fic. when i read over some of my older work i cringe bad, like, omg girl the penis does NOT work that way... but i believe everything you write has some worth, even if the worth you find is "well this sucks. i want to do it different next time." but you need to get it out of your brain before you can judge that!

i've found over time that you can never really predict how people will react to your work until it's out too, so that helped me a lot too, if that makes sense. like that person a while back who said they associate me most with the yi sang scent kink stuff even though i've only written about that a couple times. however, i can say with certainty that if you're writing about what you love, or what you personally think is hot or compelling or whatever, it will come through in the work. and it kinda sucks sometimes to acknowledge that because we're social animals and the desire for recognition sometimes manifests as "what if i just did what's popular even though it's not what my heart wants?" and that is the devil talking. YOU GOTTA HAVE FUN WITH IT!! YOU GOTTA. my most favorite pieces over the years have been the ones i got crazy self indulgent with.

hopefully this is helpful! let me know if you'd like more specific advice! and good luck out there!