Doodled through my teens, and only recently decided to really learn how to draw (started roughly a month ago, drawing almost daily.)

I suck at proportions. My heads are often too small, the distance between the ribcage and the pelvis is too far, arms are too long, and even though I'm aware of this issue I can't seem to fix it and only realise the issue too late into the drawing. I'm studying Loomis and Drawabox lessons and already read through Drawing on the Right Side of the Brain, but none of my pencil strokes feel right. What am I missing ?
I've thought about drawing ribcages and other forms over pictures using a tablet but I'm afraid it won't help my eye get used to not having a direct reference to "trace" over.

I also struggle building with forms and shapes but I've only recently started so I hope it'll click at some point, as even though I understand the concept, I can't quite apply it.

Related is my "work" and sadly, the best I can produce at the moment. Will post more.