Here are two more that you may not have come across:
Penpal by Dathan Auerbach
A Lush and Seething Hell by John Hornor Jacobs
If you find yourself in a similar situation again, I would suggest /r/horrorlit on Reddit. They are huge fans of the genre over there, and they are very generous with their recommendations. That’s where I came across The Cipher, which @NinthAcolyte suggested.
Penpal was very good. It started out as a series of postings on the “nosleep” reddit years ago, and took on a life of its own. Very creepy stuff.
I wouldn’t recommend his second book, Bad Man, though. I found it dull, too long, and not nearly as good as Penpal.
The OP is not a fan of Lovecraft, but if that aversion doesn’t extend to all cosmic horror I’d recommend Laird Barron.
Under the Pendulum Sun was Gothic and perverse.
I highly recommend the first two books in the series, Annihilation and Authority. The third one, Acceptance, had some issues, mostly that he didn’t leave the McGuffin from the first two books as a McGuffin.
I really liked the first 3/4 or so of 14 and The Fold. What I didn’t like is that the last fourth of both of those books changed tone entirely. Rather than a creepy mystery, we got a non-stop action romp. It’s like if the first 3/4 of a movie was The Exorcist ad the last 1/4 Terminator. I was hoping The Fold wouldn’t repeat the pattern, but unfortunately it did. I haven’t been able to bring myself to finish the series because of that.
There’s also Junji Ito if graphic novels are your thing. A lot of body horror in particular - he seems to have a thing about teeth.
Have you read, The Big Book of Ohio?
Check this out! https://a.co/d/gFvbCQ5
I have taken people out to see the headless Motorcyclists on Wolfcreek. After the proper headlight and blinkering signalling on the bridge.
I thought this one was pretty good. (If you like your horror mixed with SF)