My original reply was eaten, and maybe it is just as well, since it was about novel length.  I’m just going to list some authors and their works and some links.  I know finding lgbtq literature is absolutely the worst sort of experience, but if you’re having trouble with bookshops or online, definitely look into a local library, librarians can be great help.   FAR better than Google.

1. Jeannette Winterson: Written on the Body, The Powerbook, Oranges are Not the Only Fruit
2. Ali Smith – Hotel World, Like – her short story collections are magic
3. Sarah Waters – Fingersmith, Tipping the Velvet
4. Nicola Griffith – Ammonite 
5. Katherine V. Forrest – Curious Wine
6. Malinda Lo – Ash (fantasy YA)
7. Nancy Garden – Annie on My Mind (classic YA)
8. Stacey D’Erasmo – Tea 
9. Jackie Kay – Trumpet (also look for her poetry)
10. Alison Bechdel – Fun Home, Dykes to Watch Out For

(I’ve mentioned Emma Donoghue more than once, so won’t repeat here)

Definitely read Virginia Woolf – Orlando is classic as is Patricia Highsmith’s The Price of Salt (the book upon which the recent film Carol is based).   

For non-fiction, and if you’re interested in Woolf and her contemporaries (especially Vita Sackville-West), read Diana Souhami’s Mrs. Keppel and Her Daughter – beautifully researched story of the favourite mistress of Edward VII and her daughter, Violet, who carried on a mad love affair with Sackville-West for most of their adult lives.   It’s heartbreaking, funny and full of irony (Keppel was the grandmother of Camilla Parker-Bowles, who became mistress of another Prince of Wales though they later married).   

Another great non-fiction read is Hermione Lee’s masterful biography of Woolf. There is nothing dreary or boring here and I consider it required reading for young writers, anyone who identifies as queer and neurodivergent.  

Now, all this said, perhaps the best place to look for quality lesbian literature these days (for free) is online through sites like Archive of Our Own (Ao3) – look up Lexa/Clexa fan fiction (The 100) and you’ll find some wonderful writers who are pushing the boundaries of what fan fiction can be (other fandoms are surely doing so as well, but I’m mostly familiar with Clexa at this point).  Authors like @chrmdpoet, @unicyclehippo and @possibilistfanfiction, @coeurdastronaute, @steklir  – just to name a few – explore the broader qualities of ‘alternate universe’ tales that include not only lesbian pairings, but non-binary, neurodivergent individuals with compassion and care.   

I also want to mention two writers of fan fiction from the older Xena universe – where I first discovered fan fiction and got my mind blown on the quality of work being produced.  Vivian Darkbloom’s Mel and Janice series as well as her White Trash series are classic examples of how good fan fiction can be: novel, epic, hilariously funny and very moving.   

Brigit M. Morgan is another author who wrote above and beyond, with her tragically unfinished Apocalypse series, she offered a bold, mature and breathtaking look at Xena’s story, especially following her death in one of the most cinematic takes that could easily have been made into a follow-up film.  Her shorter fiction goes even darker in places, with blunt trauma examinations of celebrity and drug addiction.    If you enjoy Clexa fan fiction, it would be worthwhile to follow up on these marvelous precursors – you’ll find so much of what current fan fiction is built upon. 

So, I hope that helps a little.  Good luck and do share what you find!

ETA: I’m really ashamed of how white this list is – which just goes to show how that as difficult as it is to find lesbian literature, it is somewhat harder to narrow it down to those who are so often left out of even that incredibly small category.  I’ll keep looking and hope others post their findings, too.