With your connection, your never going to see much better then 30-35kB/s
You should set your global max upload speed to 12-13kB/s, which will leave just enough reserve bandwidth to handle the “overhead”, or “comunication”.
Bit torrent protocall gives the most download to those who upload the most, so unless you can get a faster service, your not going to always get more then your upload limit, but on very well seeded torrents, you may see speeds approaching 30s.