Just to clarify about the sway-back vs anterior pelvis tilt postures, I will use the this picture to illustrate the point:
Here you have your pelvis tilted forward, kind of like sticking out your stomach. This causes the back of your trousers tilted forward. Observe the position of your stomach relative to your foot, It is as if you are leaning forward on an incline slope. This is anterior pelvis tilt, and with this, you need wider trouser at the ankle and shorter back rise to create the un-interrupt drapes front to back on your trousers.
However, if you look at your upper torso and head, your head and shoulder move forward while the thorax tilted back. Although that tilting does not move your upper body further back, it is a form of sway-back posture. That is the reason.
So, different suits, the same posture. That just solidifies that this is how you normally stand, and that ascertains my initial claim that nothing OTR will fit you right in the first time. Just look at how you stand and you can see where it leads to the fit problems.
My hope is simply to raise your awareness of how you stand and how it impacts the fit of the suit on you. How you want to proceed is your own choice as this is the Internet.