Like I said, make sure your client's settings for graceful exit are all set to exit gracefully.
If you are certain that you are not seeding any of the torrents that are shown as seeding, write down all the statistics of the 35 torrents on the site and stop your client for a couple days, and then see if the numbers have changed (on the site, of course, not in your client).
If the numbers did change, there are two possibilities:
-you're actually still seeding those torrents, or
-your passkey got leaked and someone else is using it.
Note that the second possibility is not likely if you haven't seen any new torrents added and if the total downloaded amount on each torrent only shows the amount that you've downloaded (usually equal to the torrent size).
If it still really bugs you a lot, you can change your passkey. This will cause all torrents linked to your account to stop working, and you will have to either redownload all the torrent files (not the files in the torrent) and reseed, or change the tracker URL on each torrent to reflect your new passkey. Depending on how many torrents you want to have running, this process could take a very long time.