Original post: https://www.reddit.com/r/posturepals/comments/178ywpx/is_this_uppercross_syndrome/
In my opinion, the drawing is wrong, at least in the rotation of the pelvis.
However, here is my take on what I see about the real image. Since I can't see your feet, the placement of the solid green plumb line is a bit of a guess, but I'm pretty sure I'm close enough.
You are rotating your pelvis forward and down at the front. And lifting your sacrum up (at the back). Just as the blue arrow suggests. Then, you are doing the opposite rotation with your ribcage. You can see it on the slope of your sternum, which is the front of your ribcage.
These two rotations are arching the spine in your lowerback (the red curve).
You don't have a forward head posture. You have what we call "protruding abdomen". If Anything, you have a belly forward posture. That is visible by the dashed plumbline. Your face is obstructed, but again, my guess would be the white dashed line. That is behind the belly.
Start learning the alexander technique. That will help you, but it's a fair bit of involvement.
Start watching these: https://www.youtube.com/watch?v=6Z_IZvWMlDg , and when you get to the end or have questions, ask for more info.