From what I have read in this forum you have done everything right to get good torrent speeds. Where you missing out is the sites that you are going too. If you google private trackers there is a website that tells you about current open registrations on private tracker sites. You will have to slowly make you way through them to find a good one. Otherwise you will need to find someone who will give you an invite to a site.
The two I have joined up with were both through this site and on a good torrent I pull between 500kb & 1Mb.
Also limit your upload speed to about 7kb while you are downloading so your bandwidth isn't getting used up through uploading.
Hopefully this helps