R:

If bleeding alone, as you seem to be doing, two things will help:
1) Remove the bleeder screw from the slave cyl., and dry the threads with brake cleaner or similar. Then wrap the threads with teflon sealant tape; use enough turns to ensure a fit in the cylinder that will not leak air back into the cylinder.
2) Obtain a "one-man" bleeder bottle with check valve. The check valve prevents re-entry of air each time the pedal is released.
Here is an example:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjkjKnrrIrsAhUO7J4KHRlSBGcQFjAAegQIAhAB&url=https%3A%2F%2Fwww.amazon.com%2FAllstar-Performance-ALL11017-Bleeder-Bottle%2Fdp%2FB00F9XHVKA&usg=AOvVaw16ByXm_YPXQVGEXPtFEjp8
These bottle/check valve devices are common in racing.

You mentioned having about .5 inch of free play at the pedal; that should be enough to ensure that the clutch master cyl. inlet port is cleared by the piston when the pedal is released. Are you familiar with the eccentric adjustment for the clutch master push rod? The clearance can be reduced after bleeding.