Former acquisition editor here.
Unless a story sold for real money, do not mention it.
The only thing that gives you cred on a resume is if another editor PAID for your words.
Stating that your fan fiction placed at various sites just makes an editor roll his/her eyes at your lack of professionalism. It could even count against you.
Your submission stands or falls on its own merits. If I think it is publishable and will make my venue money I will buy it. Don't try padding things with something on the level of "My mom really liked this!"
All writers start unknown and unpublished.
All editors and agents know that.
They are anxious to find a diamond in the slush. Write a diamond and make a sale, then put THAT in your next query.
The only thing I'm interested in seeing in a query is genre and word count. Your pro sales will come a far third. I used to skip the query/cover letter and jump to the story. Within half a dozen lines I'd know if the writer knew what he/she was doing.
Most stories would have been improved had the writer deleted the first 3-5 pages.
I can advise avoiding "protag wakes up" openings, along with weather reports, scenery descriptions, and any mothers looking fondly at their sleeping child just before hearing the weird noise in the house. Have an animal in the narrative just to kill it off? Forget it.
I never rejected a story for having a bare resume, but those cliches got it kicked to the curb!