Medium is another option. You can publish your short stories there and, if they gain traction, you might earn through the Medium Partner Program based on reader engagement.
Another option is Smashwords. It provides various distribution channels and has some tools to help you format and promote your short story. But you need to follow their guidelines carefully to ensure a successful publication.
You could try publishing them on online literary platforms dedicated to Bengali literature. Some popular ones are [mention specific platforms if available].
You could try submitting to literary magazines like 'The London Magazine' or 'Granta'. They often accept short story submissions from new and established writers.
Some traditional publishing houses also accept fantasy short stories. You could look into submitting to smaller indie publishers that focus on the fantasy genre. Another option is to enter writing contests specifically for fantasy short stories. This can give your work exposure and potentially lead to publication opportunities.