Piston goes in bore seal end in first, can't see you getting that wrong really, end of piston has bore that the push rod sits in, is it fully seated in this !
To me it looks like distance between clutch fork and slave is quite large.
If both slave castings mount giving same base position and piston and rod both very very close then it can only be fork position or slave piston sticking (not returning) and then being pushed out further next time pedal depressed.
Does master stroke range seem right via yoke adjustment. I normally bleed slave unmounted (just my way & not a must) and use a hand clamp hold piston and rod back then bolt slave on and operate pedal to take up slack and position piston.
Does clutch pedal feel normal when depressed, does slave rod and fork arm move back and forth when pedal operated, have seen people hydraulically pump piston out during bleeding so clutch fully disengaged & slave apply pressure on fork even with pedal up as master stroke not full range .
Checking function and parts should conclude something . PITA but excuse for a tinny and few hours in garage over weekend :-)