Tam Lynn and the Fey Queen? Triston and Elanore lost among the wee folk? The Fairy court on display.. You’ve made generous hints at the exotic nature of these creatures but I feel you could do a bit more.
You seem at times a bit lost in the verbage. That’s a crime I’ve committed myself.
An example,
‘After all this time, I had completely forgotten my natural parents, and Gelsey was step-mother to me now. I had grown to love her as my real mother.’
Nothing improper mind you but it might be tightened to a single thought, and sentence, which would give it more force.
Something like “After a time I’d forgotten my natural parents, Gelsey was the only mother I (knew/had). Just a few spots like that but feel free to look for ways to tighten the tale. Myself I find I do the verbal wandering when I’m unsure of the direction of the tale and the story tightens again once I know where it is headed.
Another thought you might consider
You’ve hinted at the exotic nature of these beings but at the same time given nothing specific they could easily be plain old Welshmen, or worse. How about instead of such mundane words as cunt, cock, and seman etc you come up with your own vocabulary. It’s amazing how obvious made up words become in context, repetition is much less a problem when introducing new words and if used consistently you may even start something. I mean arse was just a misspelled mule before the English started snickering and shag is a rug, not a verb, on this side of the pond.

A point that might need a little more clarity is the bondage scene

‘At that, Oberon grabbed me and took me to his bed, where he tied my hands and feet to the posts at the foot, so that I stood spread-eagled and immobile ’
Now I know you are technically correct in your description, but it may play against a readers preconceived notions. A reader might imagine her spread eagled across the bed, a more common use for that word. You may find it more useful to emphasize the standing part for your reader.
Simply changing “ At that(actually you could drop ‘at that’ all together) Oberon grabbed me and stood me at the end of his bed, where he tied my hands and feet to the bed posts so I was upright, open, and immobile”
Yes I’d hope for you to continue and may actually assign it if you’re not careful
Yours
Truly Mad
Lews