Google's SITE: command is one of the most powerful tools at your disposal to locate your content. It allows you to search a site specifically, in this example, Pinterest.com. Enter the site: command with your domain name in the format below in Google's search:
SEARCH: site:pinterest.com "mywebsite.com"
Using the site: command to locate Pinterest content misattributed to Google yields an astonishing 14.4 million results.
The search will yield both pin boards, and individual pin pages (recognizable by a URL with a long string of number). Pin boards appear to be more reliably indexed than the "deeper" pin pages, so many pin pages are actually missing from Google's database altogether and will not show up on search. Examining a pin board to find your content is a tedious chore. Use your browser search function to find your domain name on the pin board. Some pin boards have a reasonable number of pins that Pinterest serves to your browser in a single pass.
Tragically, many pin boards are little more than poorly managed electronic hoards, and scrolling to the bottom of the pin board will stimulate Pinterest to serve you another helping of pins. If you still haven't found your image, scroll down again for a third helping. To reach the bottom of a completely full pin board, you may need to repeat this 10 times. Some electronic content hoarders may even surprise you with a link to a second page when you finally reach the bottom of the first page.
Click on "more search tools" on Google Search page's left hand menu.
Some useful features include pages created or changed in the past 24 hours or past week, as well as "page not visited" if you're starting to lose track.