I wanted to give you a visual that might make it easier for you to see where you need to shore up your proportions, so I grabbed your most recent screenshot and did a little doctoring in Photoshop. I added in a real world reference (Mr. 50’s Dude) and then took your model and readjusted the basic sizes for you to look at.

Note how the head is smaller and most everything else is longer. I thickened the forearms and lower legs and increased the size of the feet (which could likely be made longer still, but the angle of the image made it awkward for me to show that). I also adjusted the fall of the hands somewhat, though there’s room for play there — you could make the arms slightly shorter than what I’ve shown without losing much in the way of proportion. Take a look at how Mr. 50’s elbows are actually above the green line at his waist. While he may have his hands in his pockets, which adds flex to his arms and shortens the fall of his hands, the elbows are still at a point similar to your pose.
Don’t be discouraged by all the adjustments; these are common errors. We, as human beings, tend to focus on the head and chest area of other people — those areas tend to be where the first “tells” in our body language are born. And, of course, we gravitate first to faces, which is why most cartoons aimed at young children (and children’s drawings, for that matter) tend to have oversized heads and eyes. (Although, that’s also because the oversized look echoes the proportions of a baby and young child. A year-old child’s head equate to about 25% of its body, proportionally speaking.)
Reference is very much your friend. Even pros use it constantly. 🙂
And, in case it helps, here’s a PDF of the Loomis book I was telling you about.
Cheers!