My symptoms do fluctuate and change, though very little from supplements and mentally I'm very stable.
Took some lithium orotate (with 5mg elemental lithium), but since a couple of years take a high Mg Mineral water (contains 1 g per lliter; Rogaska Donat Mg), which also contains 3mg of elemental lithium. Got about a liter per day.
My last lithium whole blood test 3 years ago came still back at 0.06, and 6 years ago at 0.05. But at that time I already started with the mineral water.