Hi and welcome, I have a fig tree in the ground, and it is 9ft. tall and wide. It's roots spread at least as far out as the branches reach.
I think you needed to put it into a bigger, deeper pot this year to allow it to grow more roots to support new top growth. Not much you can do now, except maybe carefully lift it out of that pot, without disturbing the roots too much, add another 6in. of soil under and around it for it to grow into this summer, then either this fall after the leaves drop, or next spring before it leafs out, put it into a lot bigger pot.
If you see large roots going around and around when you lift it out of there, the new pot might be a good move this summer. Re=potting in the height of summer's hot weather isn't going to be great for any plant, but that little tree's crying out for more room to grow. If you do repot it, you'll need to keep it in the shade for a week or two, to let it recover from the shock. Then gradually move it back to its spot in the sun.
