Don’t be too rigid with how you stylise your parts, if you need to make them curvy, straight etc, go for it.

Right here you have a lot of straight shapes but for pouches which are mainly a sort of type of fabric you’re looking to try and make it curvier, more of a rounded ‘slouchier’ shape to match that of fabric.

With the belt also toy around with perspective, add some half-ellipses both for the belt colour below the belt and for above the belt the colour of the shirt so it appears like it’s going around the waist.