Well, I grow in the ground, not in pots, so I'm not an expert, but in general they old school thought on water for citrus was to let them dry between waterings. Now folks seen to agree that a little too dry and you need to water a little more often. Still, not so much that you start water logging or getting root rot problems, but a little sooner, not quite so dry, may help.

If they are in the black plastic pots from HD, and in the sun all day, the pots may be cooking the roots and stressing the plants. You also may have over-fertilized them. You could try putting them on the porch and see if they start putting out new shoots in a few weeks. Or you could get a bale of straw and pile lose straw up around the pots to the rim, to keep them cool.
But it is normal for lemons to have most of the little lemons fall off, so you haven't necessarily done anything too terrible. I should also mention that citrus only bloom once a year, usually in the spring, so you'll have to be patient to get your lemons and limes! If you have no fruit now, you'll have to wait for next spring.

I would like to debate that citrus only bloom once a year. I bought a Robinson Tangerine in the fall that bloomed in December and is no in full bloom again.

I also purchased a Meyer Lemon that had just finished blooming and had a single fruit on it with no signs of growth or blooms on June 16th. I Heavily pruned the branches and roots back and as of today it is in full bloom. Maybe I am just lucky or something?

June 16th:
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July 17th:
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To answer the original question it seems as tho the plants are just super stressed, and when they get stressed they drop their leaves and fruit to survive. They are getting much different conditions than they were at HD, where they outside or inside a greenhouse in HD? I am going to guess that they were inside or at least shaded, they had to be hardened off in before just putting them in full sun. This is done by SLOWLY introducing them to the sun for a short period of time gradually working up to full day sunlight.

Stop fertilizing and watering until you know for sure they are dried out. Than completely soak and repeat the cycle. Citrus will survive slightly dehydrated better than they will flooded. The meter you are using measures the electric conductivity of the soil so if it is littered with fertilizers you will get false readings.

Are you able to post pics of the trees and their pots? I would suggest a re-potting and pruning, but as you said you are new to gardening and this may scare you a bit. Do you have any friends with a green thumb that could help you with this?

Don't expect any flowers or fruits till next year as said since the plants are so stressed, but you never know with some TLC and luck you may get some winter blooms.

Again pics would really help, and good luck!

I have a lime tree and it is full of little limes, however,
the tree is dropping leaves. What might I be doing wrong.
I am going to put it outside when the frost danger is over. Will that help? Dot