might need a repot by the looks of it, that tree isn't healthy enough to fruit right now

I agree. That tree is weak. It needs a bigger pot, a better mix, and some fertilizer.

Thanks, all. I don't see any pests, I typically water it once per week but admittedly don't have a good handle on how to discern if/when it needs water (should it be soaked once per week?) It was in a sunny window and was just moved outside now that the weather is warm. I brought it back to the nursery where we bought it to ask what was wrong and they put more soil and a handful of fertilizer in it. Attached is a picture of the roots. Think I should re-pot it today? What type of soil should I use?

No question about it, that needs the roots to be tickled then put into a larger pot. Any good potting soil will work. Do not fertilize for several weeks after repotting, and when you do use a weaker fertilizer more often, the roots can be burned by strong fertilizers. When moving it outside did you harden it off gently? If not, the leaves will burn from sudden exposure to sun.

Thanks! How do I "tickle" the roots?

That is done by using your fingers to loosen that solid mass of roots so that a lot of that old mix falls away. Then pot into a bit larger pot with a good draining mix.

Kathy, when it comes to watering, I always water my trees and other houseplants generously until it comes out of the bottom, then rest the pot on an angle against something, so the water drains completely ( have lots of holes in the pot), never let it sit in water. The next watering after that should be done only after the soil is dry about 2 inches deep, the pot with the plant feels light ( I use this clue), also I only use water that settled over night in big bucket ( no water straight from tap, especially in the winter months), the chlorine gas has to evaporate from the tap water.