Could you post pictures of your trees in their pots. What we see will make a difference in haw we assist you.

6b

Well the easy answer is that many of us use Dyna Gro Foliage Pro. This can be used on all the citrus, plus your other houseplants (if you have some).

Usually you wait a few weeks after repotting before start/resume fertilizer.

I also keep newly repotted plants in the shade for a week and gradually move to sun, especially if done during the summer. A pic of your leaf spots might help.

You might want to do a subforum search for MG citrus/palm soil; I recall people mentioning that it didn't do well for them, but I don't remember the specifics.

It seems that most people on this forum use Foliage Pro 9-3-6 (FP) which is a fertilizer that contains all of the nutrients that citrus trees require. Each time you have to water, add FP to the water and use that instead of just water. Use 2 1/2 teaspoon FP/gal of water. Get a
cheap pH testing kit - the kind used to test the pH of swimming pool or aquarium water. If your tap water is above pH 6.5, add enough vinegar to adjust it to about pH 6.5. You will only have to add give or take 1 Tb/gal. So, you will be watering with a mix of vinegar and Foliage Pro every time the tree needs water.

Check to see if it needs water by digging a couple of inches into the soil mix to see if it is damp. Alternatively, shove a wooden skewer halfway between the tree and the wall of the pot and all the way to the bottom. Pull it out and if you see particles on it, then it does not
need watering.

I have one tree that has been in MG citrus/palm soil for decades but have also lost a tree due to root rot in that same soil mix. I now use the 511 and gritty mix for all of my trees except for the one in the MG soil. You can leave yours in the MG soil but you need to be very careful about over watering or your trees will develop root rot.