Posture assessment: Grayscale1281

Feet are wrongly placed. The outsteps (yellow lines at the bottom) are clearly converging at the back. We would want them to be parallel.
The BlueAndWhite markers (ankle, knee, iliac (anterior superior iliac spine), bottom sternum and top sternum should all be on the green line. Yes, all of them.
Your pelvis isnt' tilting forwards too badly (compared to most other people), but you are still shortening in your lowerback. thats the red curve. You are shortening it because of how much you are rotating your upper torso (ribcage) backwards at the top.
This is clearly visible by the position of the sternum (top yellow line) inclining backwards a tthe top. Another dead giveaway are the protruding shoulder blades marked with the blue arrow.
If you would get someone to take an image of your back, you will see two vertical lines between your shoulderblades.
Actually, your entire mechanism of your arm is severely shifted backwards. That is another reason why you are compensating with your belly so much forwards, it's simply a balance of forces so you can keep yourself upwards.
Because the shoulder girdle is so retracted backwards, you are also lifting your shoulders too high. You will see this in a mirror, if you look directly ahead. Your clavicles will be going back and up and in the mirror it will look like a "V" shape .
You are shortening your neck cervical spine (pink line)

All 100% fixable, but not one part at a time. You will need to change everything at once.

First, you will need a thorough understanding of how the mechanism of the body works.

Then, you will need to make changes all together at ones.