>>2021515>bike just starts fallingThat's when you're supposed to catch it. Don't worry about rolling back yet. If you're doing small circles, try to lean to the inside and wait for the bike to start to fall (to the inside). When it does, pedal just enough for it to get upright again. I think it's easier to do if you turn your wheel in the direction of your front foot.
The incline helps you with the other direction and trackstanding in one place. When you can do tight circles, go to an incline and position yourself at a 45 degree angle so that your front wheel points straight up the incline when you turn it. Now try doing the same thing as when riding in circles. If the bike starts falling to the inside, pedal forward (the incline will most likely keep you in one place), but if the bike starts leaning to the outside, let it roll back.
