Amitriptyline and tablet issues

So when the CVS Aetna merger took place, all sorts of weird things occurred, including limiting dosage choice. CVS now disallows my exact Ami dosage of 30mg because that requires 3 tablets. (Shouldn’t that be illegal?) These meds take so much tinkering and I finally found a dose that seems right. But CVS is insisting i choose 1 tablet only, so 25mg or 50mg. So annoying. Last time i tried to taper off Ami, i went straight back to disability-level MAV. So I’m going to try to toggle btwn 25mg and 35mg with the last few Ami 10mg tabs i have left.

Does anyone know if a dose of Ami will have an effect that same day or if it is ultimately about having the right amount over time? Will the 25mg cause my body distress or not likely because the level of Ami in my body has stabilized?

Any insight welcome. Thanks!