Your moving it yourself, that is what your doing wrong.
Let it get its foot down, wherever it wants to. If it is the back of the tank that is ok.. it will eventually move around to the best place for it on its own, but it has to get its foot down and settled for a little bit before it will do that. By moving it you just stress it out. FWIW, I have been keeping anemones for many years now and I have never fed mine directly and they do fine. Feeding will help them, but not required, and at the point you are now, food is not the thing to be worrying about. Let it get settled first.