Assessment context and image originals from this thread: https://www.reddit.com/r/PostureTipsGuide/comments/156cf0s/can_anyone/
Some pretty standard patterns displayed.
Notice the placement of your feet on every image. Left food forward to the right one, nicely shown thanks to the flooring. Heels together, toes apart.
We would like symmetry - both heels on the same line, and the out steps of your feet (the blue lines currently converging at the back) should be parallel.
Knees released (not in full extension).
Anterior rotation of your pelvis. As the white arrows show, you are lifting your sacrum (green dot) up and pushing your iliacs down (blue dot at waist height). Since these points are both on the same structure (pelvis), they will of course move together.
Your ribcage rotates in in exactly the opposite direction to pelvis. Top sternum going back, bottom sternum forward. The slant of the sternum is showing how much you retract the top of your ribcage.
These two opposing rotations of your upper and lower torso shape the middle torso (spine) into the red curve. You are shortening your torso.
This arch in the back goes hand in hand with the protruding abdomen. In your case, you may be a little overweight too, but the belly is spilling out forwards so much mainly because your abdominal muscles are pretty much out of action.
The weight of your middle torso shifted forwards is then compensated with the weight of ribcage, arms and head / neck retracted back. That's how you secure equilibrium.
If you would adjust the movements of the pelvis and ribcage in such a way as to swap the rotations, you would start straightening the curve in your spine. For that to happen, your abdominal muscles would have to get back to work which means that you would at least cut your belly in half.
Have a look at this example here. This is one of my students. He has a similar shape of body to yours.
On the left image, he is just standing his usual way. No conscious guidance or control of his movements what so ever. Observe the shape of his torso just like yours. He is a big belly boy.
On the other image (couple of weeks later) he is performing some "gesture" I got him to do. He is stretching the bicycle tube wrapped around his back. Although not perfect yet, you can clearly see the curve in his lowerback has decreased. And you can also see he lost his belly, as in order to straighten the spine he must engage his abdominals (amongst other things).
I think even to an untrained eye, this change is visible.
The camera wasn't quite square to the environment (and you) so I didn't bother with the plumblines on the front and back views, but you can clearly see the right shoulder lifted. That has to do with the twists in the body.
Let me know if you have more questions.