In post #22 you show two completetly different schematics:
1) The one on the left is from the datasheet and has an opamp.
2) The one on the right is yours that does not have an opamp and is wired completely differently.
Why don't you use the circuit from the datasheet and feed its output through a coupling capacitor and attenuator to the volume control then to your LM386 power amplifier?
The maximum output from an LM386 that has a 5V supply is 3V p-p when it drives an 8 ohm speaker. Therefore its max input is 3/20= 0.15V p-p.