On the leaderboard page, I have 8 hats. Or 9 hats. I'm bad at counting and it's really hard to tell.
Leaderboards are heavily cached - they'll update eventually. The correct hat count is visible on your profile page (which will show your overall hat count across all sites, rather than the individual hat count for the site you're on).
If you want your current per site hat count, the leaderboards are your only option (without manually clicking on each hat to see where you've got it and adding them up yourself) but these do at times take some time to update.