>>40977590I tried quite a few different reverse search websites (such as
iqdb.org,
saucenow.com, and
tineye.com) and search engines (Google, Bing, and Yandex). These websites are all worth a shot, as none is 100% perfect for each image. Typically, these websites give you the option to use a direct URL of the image you want (it cannot be the page you found the picture on; right click and select "open image in new tab," then copy the URL of the new tab), or the file if you've downloaded it onto your computer. These websites will then try to find you a match, on Pixiv, Deviantart, or another service. If you can only find a higher quality version, you should try using the better quality image on one or more of those sites again, as it might increase your odds. If you can find a version with the artist's username, that may be the ticket you need to finding the source. Good luck, and if you have any questions about sourcing a particular image of yours, I'd be happy to help.
