The plant is growing well, height wise but has still not produced any flowers yet - any ideas as to why not?
This is, likely, due to having too much nutrients (mainly nitrogen) in the soil. It may be a few years before you see blooms. It will require nutrients to leech out, slowly. This article will help you with its care:
https://www.gardeningknowhow.com/ornamental/shrubs/broom-plants/pineapple-broom-plant.htm