It looks like in your case, you may have been caught in an old system glitch. I will now go ahead and do a reset for you that should fix this.
That being said, be aware that if you have any torrents for which you have not downloaded 100% of ALL the files in the torrent, the system will only register you as leeching the torrent, which will make it count towards your maximum number of simultaneous downloads.
In just a couple of moments, your account should be all set and you should be good to go.
Lastly, please be aware that when you stop a torrent, it often takes some time for the torrent to time out on our end and free up the download slot.