I'm in the "not swapped ends yet" camp at the moment. Nearest I got was when one of the brake cables pulled out of its attachment leaving me with full brake on one side and none on the other. Now I tend to use them for steering rather than slowing down.
A couple of thoughts.
Assuming your tailwheel is NOT free-castoring are you ensuring that it is properly locked before take off? We have the Maule tailwheel, which has a spring-loaded bolt to engage the steering horn with the kingpin. The bolt is released by a cam when the steering angle passes a certain point and should re-engage automatically when you line up. However if it is mucky or lacking lubrication it might not do so and our tailwheel has even been seen doing 360's all on its own while taxying. You can check whether it has re-engaged once you are lined up by pressing on the rudder pedals. If they are relatively free-moving you ain't locked.
Second thought. For the tailwheel to be effective as a steering device it needs some weight on it. Do you have the stick hard back on the landing roll? If not the tail can be light or even bounce back into the air, making it easy to weathercock.
Mike