I know some places (most of them I check every week).

1 Archive of our own
Fanfiction based but original tag allowed.
https://archiveofourown.org/tags/Guro/works

2 Aryion
It is not all about vore, some authors already posted here many nonvore stories.
Make sure to add tags, especially "willing" or I won't find it because so many stories each week.
https://aryion.com/g4/latest.php?type_search=Writing

3 Lolicit
I recently got access to it through loli of the day thread and don't know where exactly it is allowed to post guro stories:
in guro:
https://www.lolicit.org/forumdisplay.php?f=97
or in stories (in rules tag guro exist):
https://www.lolicit.org/forumdisplay.php?f=12

4 All the Fallen
Similar to lolicit with easy access.
No guro section but in stories I found snuff tag.
https://allthefallen.moe/forum/index.php?forums/loli-stories.20/

5 Pulptoon
http://www.forum.pulptoon.com/forumsXenforo/index.php?forums/story-corner.9/

6 Ravishu
Also some time ago I found this site.
http://ravishu.com/forums/index.php?board=88.0

7 ASSTR
It is still alive.
https://www.asstr.org/files/Authors/?C=M&O=D

8 Pixiv
I know about dozen of artists who posted here in english, but they often don't use tag "english" so it is hard to find them).
https://www.pixiv.net/en/tags/R-18G%20english/novels?s_mode=s_tag