Wow.
You aren't too bad with portrait drawings. The faces look rather nice. The noses look rather big, but other than that, they look good.
The only thing I see that bothers me in your older drawings was the bodies of your characters are a little lacking. They don't seem as well drawn as their faces. The arms especially.
I am not much of an artist, so I am not good for feedback when it comes to drawing. However, I do know that you should avoid rubberman-like arms. You should also be sure to get the lengths just right of the arms, so that they don't look too short compared to the rest of the body.
However, your work is good. Better than anything I could do and if you just keep drawing and trying to improve yourself, you will become better than you are now. Practice is key. I hope to see more work from you on MR. Should be exciting.
Don't give up, even as you get older!