NIce work man. I'm also struggling with wireframes from imagination, it's easier to deconstruct existing photos, but getting good angles from imagination is hard.
I couldn't help but notice a few things in these last ones, did a quick edit to try to explain what seemed off:
I feel like proprtion for head, torso and hips also need to be a bit more proportional, since our head is not the same size as the other two. Here's an example:
Still learning myself though, bests of luck!