Yes, to measure inseam take your outer pants and shoes off, stand against a wall with your feet maybe 8" apart, put a book between your legs and against the wall, slide it up until it won't go any higher, measure.
Thinking about that saddle some more, it seems to me that one can't hang one sit bone off the saddle and still pedal. The saddle horn will prevent that - unless you're so far forward that you're sitting on it. Then it's possible to slide sideways enough to hang one side off. Seems to me that if you just push back and the saddle horn is between your legs as you pedal, both sides will have to be on the saddle. Unless the saddle is too narrow, that is. What's your sit bone measurement and how wide is your current saddle?
While riding, if you sight your top tube against your down tube, and your stem against your front wheel, does it seem that your head is on the centerline of the bike or are you tilted one way or the other?
The right side and left side photos are interesting in that the leg you complain off being off the saddle looks shorter than the leg that's fine. Might you have a bit of scoliosis? Are your hips tilted a bit?
KOPS is not a thing. Set your saddle set-back by balance, not by where the pedals are. My fit primer is here:
How can I fitting my bike