A picture is worth 1000-words.
Do you have any sort of anti-sway bars on the lower link arms of your 3-point hitch?
Lift the 3-point with the cutter attached. Walk to the back of the mower, grab the wheel or something back there and move the mower back-and-forth (left-to-right). How much movement do you have? When lifted, can you get it straight behind the tractor?
Here's a pic with sway bars attached. Outside of your lift arms, connected to the bottom of the axle. There's other variations of these as well.