Hello! My container lemon is in a bad way and I'm at a loss. Sorry - I know that everyone posts troubleshooting questions about their meyer lemon trees. I swear that I have read as much as I could before resorting to making my own post like this.

In late February, I noticed signs of spider mite infestation: some webbing at the junction of the branches and also I could spot an adult mite or two when looking carefully at the back of some of the leaves.

I started spraying the tree with neem oil from Bonide in March. When that did not stop the leaf damage I added a sprayable insecticidal soap from Bonide in early April. Initially, I was spraying the soap onto a paper towel and using it to wipe down all the branches and leaves (front and back) every few days.

Now I am just spraying the soap (careful, again, to get the backs of the leaves) liberally onto the tree every few days. When it dries, I do the same thing with neem oil. About once a week I lug the tree across the apartment into the shower and hose off the leaves.

Aside from leaf damage, I have not seen any evidence of mites since early March. There is no webbing and I have not seen a single visible mite since then. It's just that the leaf damage is still getting worse. I can't tell if I'm doing too much or too little or the wrong thing entirely.

It still has many leaves but the rate at which they are dropping is accelerating (a few per day now, and more on days when I hose it off in the shower, understandably) and they are dropping with less evident damage -- often just a few dark spots around the base of the leaf.

Questions:

1. What can I be doing differently?
2. Should I remove the lemons? Would that help at all?
3. When is it a lost cause?
4. Am I correct that this seems to be spider mites? Or should I also be using a fungicide?

I would be very grateful for any advice you can give me.

Misc tree details:

• 3-4 years old; I've had it since late august 2019. It flowered in the fall and is currently bearing unripe lemons.
• It's potted in a fast-draining 5-1-1 (pine bark-perlite-peat) medium and I water it when the top couple inches feel dry
• Shortly after I got it (so, early fall 2019), it had fungus gnats. It didn't sustain any visible damage from the gnats and they seem to be gone now; I used mosquito bits to discourage them.
• I have no outdoor space, so it lives inside all the time. It is by the windows in a south-facing sunroom; since I live on kind of a shady street, I also have it under LED lighting.
• I've fertilized it with a couple things, including fish emulsion, dynagro foliage pro (9-3-6), and most recently I mixed some osmocote plus smart release into the top layer of medium.

Now, a bunch of photos:

^Many of the leaves that are now dropping have much less evident damage than this.

^this is the front side of the leaf from the previous picture

^It no longer has any leaves with this much obvious damage. I have removed them or they have fallen off

^I see the tip burn on this leaf. Several of the older leaves near the trunk have exhibited tip burn in the last month and after doing some research I thought it was probably due to salt buildup from fertilizer. I've flushed out the container medium since then and most of the burned leaves have dropped anyway due to mites.

^This is what the tree looked like on May 8. I did prune some of the straight-up growth after this photo was taken. It doesn't usually live in the shower; it's just in there to be hosed off.

^This is what the tree looks like today.