Two possibilities spring to my mind. One is that it needs to grow new roots in order to establish itself again, which means that that will take up most of its energy. Therefore the leaves are small but it's enough for photosynthesis. It's a good idea to remove the blossom 'cause then there is no energy "wasted".
Two; You may have re-planted it too deep and therefore the roots don't get enough oxygen. If that's the case you can take some of the soil off the roots now and I would advise you to re-plant after the leaves have fallen in late Autumn.
A picture could make the trees situation much clearer.