There are three sources of information.
One is what you know, the bi-monthly FINRA report that is reasonably accurate at reporting the open interest.
The second is the bi-monthly SEC report on FTD (fail-to-delivers). Those are almost always very small. Search "SEC FTD" and you can find it fairly quickly. Download the file and unzip and you will see fairly raw data.
The third, and the one that often get pushed by people asserting "naked short numbers" is the daily trading activity. Every trade is marked as short or not, and if short will be marked as "exempt" or not. The sites that tabulate daily trading shorts are using this.
But the daily number does not mean anything near what many think. If a market maker buys a share at 1:01:40 PM and sells it right back to somebody else at 1:01:45 PM, the first transaction is short. And it will also be marked as exempt, which the websites will say is naked. In reality, all they did is their normal market making activity.
Market Data 
Markets 
AI
