My Kumquat tree is 4 months old has plenty of fruit , but fruit falls off before full maturity.
Certified GKH Gardening Expert
For the most part, this is completely normal. They drop a majority of the fruit in order to make sure that what stays on the tree gets the nutrition it needs. Here is an article for help. It is about lemons, but all citrus have the same general care and problems. The article can be found here: https://www.gardeningknowhow.com/edible/fruits/lemons/lemon-tree-fruit-drop.htm