I've got a crazy idea that no one seems to have suggested yet. It looks like you're using the standard BT port numbers (6881-6889). Try changing your BT ports to something above 50000 and see what happens. I know your ISP claims they don't throttle traffic, but that doesn't mean they're being honest with you. Now this won't work if they're actually monitoring the packets instead of looking at which ports your traffic is on.