This definitive site for low power has a basic mosfet switch circuit for devices attached.
It also addresses many of the issues that make a truly low power sleeping device a bit of a challenge; you did mention a lack of success, so perhaps here you would find good advice.
There is no substitute for measuring the current when you are chasing the last microamperes.
A cell phone picture of a hand drawn schematic is a good and easy start to sharing your wiring concepts.
What touch sensing device or technique are you using? Obvsly it will need to be actively listening for a touch, this will be the lower limit to the consumption of power, indeed it will probably be able to make it 99.99 percent of the power used in sleep.
a7