Luv, is your tree grafted? Lemon's have thorns, period..I don't know if cutting them off is a good idea. Did you fertilize in summer? Feeding is important and begets citrus to bloom/fruit. Toni

Epsom salt (Magnesium Sulfate) won't hurt anything; but it is probably not necessary. I don't see any signs of Mg deficiency; but Meyers are heavy users of Mg. My field formulation of fertilizer has 2% Mg; and BTW I put Magnesium Sulfate on my roses twice a year; and I always sprinkle some around my garden Meyers at the same time. I would also lose the stake; try moving the ties down 3-4 inches every couple of months until you can remove them altogether. You have quite a bit of weight of lemons relative to your trunk size/strength; so if you just removed the stake now, you would risk the trunk breaking.

Oftentimes, the damage caused by over watering cannot be 'fixed' by drying the soil out. Planting into a VERY coarse, rapid draining potting mix can go a long ways in preventing problems in the first place, even for those who tend to be chronic over-waterers. LOTS of us are guilty of this at some point, lol! Using a great deal of perlite, bark fines, and/or Turface (for example) insure that you'll have plenty of large pore spaces in your potting mix to promote the essential water drainage and a constant oxygen supply required for healthy root growth within a container. Please know, too, that moisture meters are notoriously inaccurate.

Is the bird allowed to roam freely in your home? If so, it could have shredded a few leaves. My friend's mom had a parakeet that they let out sometimes. When they weren't looking it often would shred the paper towel roll or a magazine. It didn't take long either, couple minutes of them not looking. It was like the bird watched them and as soon as their eyes were off it, zoom! shredding done, lol!