Start from, where you like, I just can’t seem to make heads or tails of your poly flow.
Don’t take this as harsh criticism, just part of the learning experience.
The ref looks like a good simple design to start with, just take it one step at a time. do a basic body outline devoid of any detail like ridges or weapons or what have you. just "white box " it get the basic shape in there, then refine the details from large to small.