My first reaction is your stool is awfully high. When concert guitarists play onstage they usually use a piano stool. When I sit on too high of a seat I end up having to use my hands to hold the guitar in my lap. It should be stable in your lap without having to hold it.
Compare with the posture of a few others:
Andres Segovia. Much lower stool. The whole guitar is much higher on his body. Segovia is shorter and rounder than you, so,
Christopher Parkening. He is tall, built more like you. Also using a lower stool with the guitar higher on his torso. He is holding the guitar at a slightly higher angle.
Julian Bream. Once again, lower seat.
All their left knees are at a higher angle than your photos and the body of the guitar is higher.
That said, Old John has a very good point that you must be able to sit in that position for long periods of time without back or shoulder problems. The angle of your wrist is also a concern. Your left wrist looks like it’s bent a little farther than I would suggest. Spending a lot of time with your wrist bent too far can cause long-term problems. That’s one problem I have on electric guitar now that I’m older. I get a bit of carpal tunnel from my wrist angle and end up with numb fingers.