I have been growing indoors a fig tree. It is 5 years old. It has fruited, but fruit drops. Reading your information, pollination is required by insects. I have no insects in the sun room. What gets pollinated? I see no flowers. Would a second fig tree be helpful? Living high in Colorado, it is too windy and cold at nights for putting the tree outside. Done that and the wind just ripped the leaves to shreds. So hard to protect the tree. Waiting for the luscious fruit.
Fig Tree – Brown Turkey
Certified GKH Gardening Expert
Since your fig is kept indoors, the lack of pollination could certainly be a contributing factor. You do not need another fig for these plants to bear. If possible, keep your fig outdoors during the day and bring it in at night. You could also place it in a protective area that offers shelter from the wind. Another factor could be water. Container plants dry out quickly, especially trees. Here is an article that you may find helpful: https://www.gardeningknowhow.com/edible/fruits/figs/fig-drop.htm