Hi! I live in Thailand on a Non-B visa and left the country in November to go to the U.S. for a few days. Does my 90 day reporting start from the day I re-entered Thailand on Nov 8? 
The agent at immigration took my 90 day slip last month when I went to renew my visa so I don’t know when my 90 days is up. I don’t even know what the point of this reporting is to try and figure this out on my own 😅 Any advice would be appreciated!
TLDR : Answer Summary
Yes, your 90-day reporting countdown starts again from the date you re-enter Thailand, which in your case is November 8. It's important to note that if you are on a single entry visa or a regular extension, you will need a re-entry permit to maintain the validity of your visa upon leaving the country.
90 DAY REPORTING RESOURCES / SERVICES
- Use the trusted Thailand 90 Day Reporting Service to get your in-person report done and mailed to you for as low as 375 THB (even if the online system doesn't work for you).
 - For immediate assistance, contact Thai Visa Centre directly via LINE at @ThaiVisaCentre or Email them.
 - Join the Thai Visa Advice Facebook Group to ask your questions, and get advice from others.