On the aforementioned Homestuck Fanauthor Coalition, I've seen plenty of writers barge in and ask for confirmation of whether or not they should be do X or Y and it puzzled me at first. They're writing fanfic, isn't that the 'do what you want forever' genre?
Of course, there's "shipping discourse". But it's my blog and I'll pretend most people are grown adults and don't engage with media like toddlers. Aside, most people who have these doubts also don't give a single shit about that kind of thing.
What I find, in actuality, is that most people are afraid of judgement.
Some of them are aware they're afraid of being judged. Some are unaware, but still are afraid of "something" happening to them if they write "something wrong". What counts as "something wrong" varies from person to person, but it's usually not that risqué. If it's taboo, it's usually something thousands--if not millions--have written it before. It likely has showed up in mainstream media.
I'll be realistic: Nobody will judge you because barely anybody will notice what you'll write. Write whatever you want. Have confidence. The couple people who see your work will love it.
I can't bother finding a way to fluff up this article. Just write what you want, fucker. You'll be alright.