Hi Dave. The soil you linked to is not a good soil for Citrus. It is too fine and spongey. Citrus needs soil which is VERY airy and has chunky matter that leaves pockets of air, and nothing that holds onto moisture. It would rather be dry, to the point where it would do better growing in gravel with no soil than what you linked to (there's even a soilless growing medium called "gritty mix" you can google). A popular mix on this forum (I use it myself) is known as 5-1-1 and is mixed from 5 parts Reptibark brand small bark chips, 1 part "Citrus soil" or Peat moss, 1 part Perlite. All in all fine textured dirt and compost causes death in citrus.

Separate from your soil problems, you stated that you recently moved. Meyer Lemons seems to drop leaves very readily when their conditions change.