I have a star fruit tree. It is in a pot. I don't know how old it is because I bought the tree at a farmer's market. It bears nice sweet juicy fruit. They can take a little shade and still flower so if yours is getting plenty of sun, it should fruit if it is old enough. Was your from a seed? I am not sure how long they take to flower from seed. The starfruit I have had from the supermarket are much more bland than the ones from our little tree. I have to find them before our turkeys do because they LOVE the starfruits and will even try and get their big fat bodies up onto the large pot to reach the higher ones.