You might want to try container growing for this fig. It would give it the chance to develop a more robust root system which in turn will give the tree more nutrients for growth. When using containers you also have the option of moving the plant to a better location for sun.

Can you show some close up pictures of the trunk so we can see the internode spacing? Often being grown in a container will dwarf a tree, temporarily, because of 2 different restrictions that formed in the container.

The first is in the roots, container plants often grow long roots that circle the outside and do not branch much, the tips of the roots get further and further away from the trunk so they draw less water. There is also the chance that tangled roots will girdle each other and reduce growth. It takes time for an older container tree to adjust and grow a natural fibrous root system after being planted. Nurseries often recommend slicing the sides of the root ball to shorten the roots and increase their branching.

The second is in the trunk, giving a fig tree everything it needs in a container is difficult and it will undergo periods of reduced growth due to becoming root bound, repotted, drying out, not getting enough fertilizer etc. The trunks and branches that form during these times are thin and have short internode distances and cannot transport water well.

Think of the trunk and roots as straws that the leaves use to drink water, the thinner and longer they both are are the less water the leaves are able to get.

So removing most or almost all of the top probably will help the tree to grow more vigorously (would still like to see pictures to confirm short internodes though). With these cuttings you could produce larger and stronger plants than the mother by the end of the season if you plant them in a good location.