Sounds like you're doing everything wrong.I raise citrus in Florida.

I was sorta thinking long the same lines.

Use ONLY citrus fertilizer found at Home Depot type stores. Keep barely
moist in a full sunny location.No wet feet. Cut all suckers off ,all
the time,anytime.Fertilize early spring and late spring.VERY LIGHTLY
for a potted plant. Good luck

Thanks. I think the leaf drop is seasonal, it has happened before
after bringing the pot in from outdoors, where it lives during the
summer/fall. This year I kept it out later than normal, and it
probably just thought it was the right thing to do. I don't recall it
blooming without leaves, though. There are just a handful. The
rootstocks will get pruned out later this spring, and I'll watch the
moisture better. Hopefully that will help!