It's important as a writer to remember that you do not have to have personal experience with everything you write about.
I wrote a V triad before I even knew the term, and included a threesome sex scene in that novel. Not something I'd experienced.
I write romance novels about gay men. I'm neither gay nor a man.
I write teen fiction about teenagers who are gay, lesbian, or transgender. I've been a teenager, but not any of the other things.
On a slightly silly note, I write romance novels about werewolves. I'm not a werewolf.
All of these things have been published by various publishers who pay me for my work and have pretty strong quality control as to what they put out for public consumption. My lack of personal experience/knowledge has not kept me from writing authentic, realistic characters and situations.
Writers frequently hear "Write what you know," but I think that's phrased poorly. It should be "Know what you're writing." Do your research. Read. Talk to people who've been there if you can.
It doesn't matter whether you're sexual or asexual, romantic or aromantic, what your orientation or gender identity is. You aren't writing about yourself, and if you take the time to learn--as you seem to be doing here--about the types of characters and situations you're writing, plus use your brain and your knowledge of human beings in general, you should be fine.
Me: 43, cis-het female, poly
Hubby: my husband, 41, monogamous
Guy: my LDR boyfriend, 42, rebukes all labels