This is why i think that she is root bound.
If you take a look at the bud sets in this pic
You can see that she has started to flower but her buds are not set. Take a look at the crown/ head formation
it is not fully developed and has not lifted. When my buds are coming in at this phase there is still a bit of stretch
in flower until the crown bud forms. Seems that once that happens the rest start to fill in its almost like a trigger.
IF this plant is pot bound there was no room for the roots to develop as she finished her last bit of stretch heading
into full flower. As they are entering flower, they still produce roots, actually i dont really think that they stop.
If there is no room for this than the bud development will slow as well leaving the plant in a hibernated state.
When you go to transplant take a pic of the roots i want to see them if you dont mind.
But i bet once you get her in a new home and she settles i bet she grows a little more and then starts filling out