I'm not sure you're doing anything wrong, to be honest, from what you've described. For what it's worth, we're now at the end of the dry season and the rosette is probably the smallest it ever is, just as a natural consequence of the drought ... that will begin to reverse in a month or two and your tree probably will look leafier by spring. That wrinkle of course does not explain why it has not branched, but maybe others with more experience here will have an explanation.
